Biomedical subjects

E A Edwards

Publications and source records attributed to E A Edwards.

At least 19 recordsLinked to original sources

PubMed2006

Dechlorination after thermal treatment of a TCE-contaminated aquifer: laboratory experiments.

A microcosm study was conducted to evaluate dechlorination of trichloroethene (TCE) to ethene and survival of dechlorinating bacteria after a thermal treatment in order to explore the potential for post-thermal bioremediation. Unamended microcosms containing groundwater and aquifer material from a contaminated site dechlorinated TCE to cis-1,2-dichloroethene (cDCE), while lactate-amended microcosms dechlorinated TCE to cDCE or ethene. A thermal treatment was simulated by heating a sub-set of microcosms to 100 degrees C for 10d followed by cooling to 10 degrees C over 150 d. The heated microcosms demonstrated no dechlorination when unamended. However, when amended with lactate, cDCE was produced in 2 out of 6 microcosms within 300 d after heating. Dechlorination of TCE to cDCE thus occurred in fewer heated (2 out of 12) than unheated (10 out of 12) microcosms. In unheated microcosms, the presence of dechlorinating microorganisms, including Dehalococcoides, was confirmed using nested PCR of 16S rRNA genes. Dechlorinating microorganisms were detected in fewer microcosms after heating, and Dehalococcoides were not detected in any microcosms after heating. Dechlorination may therefore be limited after a thermal treatment in areas that have been heated to 100 degrees C. Thus, inflow of groundwater containing dechlorinating microorganisms and/or bioaugmention may be needed for anaerobic dechlorination to occur after a thermal treatment.

Bacteria↗

PubMed2006

Effect of phosphorus limitation on microbial floc structure and gene expression in activated sludge.

The effect of limiting phosphorus (P) in activated sludge was investigated in laboratory-scale sequencing batch reactors (SBRs). Correlative microscopy revealed that P-limitation (COD:N:P = 100:5:0.05) leads to morphological changes in floc structure and the composition of extracellular polymeric substances (EPS). This was found to be accompanied by expression of quorum-sensing in an acyl homoserine lactone bioassay. Differential gene expression in relation to P-limitation was examined in a global profile using the Affymetrix Escherichia coli antisense genomic microarray. Three separate experiments were conducted where the impact of P-limitation was examined under batch conditions and in SBRs at stable operating conditions and within 3-7 days following a down-shift in P. Significant changes in open reading frames (ORF) and intergenic regions based on the E. coli microarray were observed. Several genes associated with cell structure, including slt, wbbH, fimH, amB, rfaJ and slp were found to be expressed. Quorum regulated genes were also found to be expressed including psiF which is known to be induced by P-starvation (92% confidence level; 1.45 log ratio).

Escherichia coli↗

PubMed2005

Nitric oxide levels and ciliary beat frequency in indigenous New Zealand children.

New Zealand children's morbidity from respiratory disease is high. This study examines whether subclinical ciliary abnormalities underlie the increased prevalence of respiratory disease in indigenous New Zealand children. A prospective study enrolled a group of healthy children who were screened for respiratory disease by questionnaire and lung function. Skin-prick tests were performed to control for atopy. Exhaled and nasal NO was measured online by a single-breath technique using chemiluminescence. Ciliary specimens were obtained by nasal brushings for assessment of structure and function. The ciliary beat frequency (CBF) (median CBF, 12.5 Hz; range, 10.4-16.8 Hz) and NO values (median exhaled NO, 5.6 ppb; range, 2.3-87.7 ppb; median nasal NO, 403 ppb; range, 34-1,120 ppb) for healthy New Zealand European (n=58), Pacific Island (n=61), and Maori (n=16) children were comparable with levels reported internationally. No ethnic differences in NO, atopy, or CBF were demonstrated. Despite an apparently normal ciliary beat, the percentage of ciliary structural defects was 3 times higher than reported controls (9%; range, 3.6-31.3%), with no difference across ethnic groups. In conclusion, it is unlikely that subclinical ciliary abnormalities underlie the increased prevalence of respiratory disease in indigenous New Zealand children. The high percentage of secondary ciliary defects suggests ongoing environmental or infective damage.

Adolescent↗

PubMed2005

Paediatric home ventilatory support: the Auckland experience.

OBJECTIVES: To examine the trend over time, describe the disease categories treated, intervention success and outcomes of the children treated at home with continuous positive airway pressure (CPAP), non-invasive ventilation (NIV) and ventilation via tracheostomy (invasive ventilatory support, IVS) by the Respiratory Service at the Starship Children's Hospital in Auckland. METHODS: A retrospective review was undertaken of the Respiratory Service records from November 1991 to February 2004. RESULTS: Home CPAP, NIV or IVS was initiated in 160 children (89 boys, median age 6 years) in the study period. Sixty-nine (46 boys) remain on support and are still actively managed by the Starship Respiratory Service, of whom 46% live outside the Greater Auckland Region. Despite 42% of children being less than 5 years of age at initiation of therapy, institution of support failed in only 11%. The majority received treatment by non-invasive mask interface (68% (n = 108) CPAP, 29% (n = 47) NIV), with only 3% (n = 5) supported via tracheostomy. The numbers and complexity of support rose over the 12 years. Respiratory support was discontinued in 57% of cases, after a median of 12.5 months (range 3-52 months); in two-thirds, support was no longer required due to an improvement in the medical condition. The most common indication for support in current patients is respiratory parenchymal or airway disease followed by neuromuscular disease. Obesity is not a common indication. CONCLUSION: This review documents the increasing trend in children receiving respiratory support at home. Future planning and resources are needed to address this growing need.

Adolescent↗

PubMed2004

Sending children home on tracheostomy dependent ventilation: pitfalls and outcomes.

In spite of the consistency of the primary discharge coordinator in our practice and attempts to streamline the process, the obstacles to discharge highlighted five years ago remain frustratingly similar. The children in this survey spent an average of 9.6 months extra time in hospital awaiting discharge at considerable cost to the local commissioning teams, quite apart from the emotional cost to the child and stress for the whole family. We hope in future years this review will enable health practitioners and local health providers to anticipate the hurdles, address the problems early, and expedite the process of discharging home children who are dependent on long term ventilation via tracheostomy.

Adolescent↗

PubMed2004

HRCT lung abnormalities are not a surrogate for exercise limitation in bronchiectasis.

In paediatric bronchiectasis, there has been limited work on the relationship between disease severity as assessed by exercise limitation and high resolution computed tomography (HRCT). An observational study was performed on 36 children who completed a questionnaire, physical examination, spirometry and sputum analysis, followed by a low dose of radiation protocol chest computed tomography (CT) scan and cycle ergometry incremental exercise test. A modified Bhalla score was used to score the HRCT abnormalities. The exercise variables used to assess functional status were heart rate, oxygen consumption, oxygen saturations and time of exercise. The results were compared with established normal paediatric values. The median (range) age of the children was 13 yrs (10.6-17.1). Age, sex, height, weight or pubertal status were equally distributed between the children with cystic fibrosis (CF) or non-CF bronchiectasis. The children with non-CF bronchiectasis had a lower median forced expiratory volume in one second % predicted than the children with CF (69% versus 76%, respectively). The distribution of lung disease differed between the two groups. The children with CF bronchiectasis had predominantly right upper lobe disease, and scored higher for the presence and extent of bronchiectasis. Otherwise, there was no statistical difference in the overall CT score or the individual CT parameters between the groups. There was evidence of exercise limitation in both CF and non-CF bronchiectasis compared to normal children. No consistent relationships were identified between the lung function parameters, HRCT findings or exercise parameters in either disease group. In this study, high resolution computed tomography features were not found to be markers of exercise capacity. As spirometry, high resolution computed tomography features and exercise testing give different information in children with cystic fibrosis and non-cystic fibrosis bronchiectasis, the current authors suggest all three may be required for the comprehensive assessment of respiratory status.

Adolescent↗

PubMed2003

Retrospective review of children presenting with non cystic fibrosis bronchiectasis: HRCT features and clinical relationships.

Non cystic fibrosis (CF) bronchiectasis in children presents with a spectrum of disease severity. Our aims were to document the extent and severity of disease in children with non-CF bronchiectasis, to review the inter- and intraobserver agreement for the high-resolution computed tomography (HRCT) features examined, and to assess correlations between HRCT features and clinical measures of severity. We performed a retrospective review of 56 children from the Starship Children's Hospital. HRCT scans were scored by a modified Bhalla system, and the chest X-rays using the Brasfield score. Scores were correlated with demographics, number of hospitalizations, disease duration, pulmonary function, clinical examination, and chronic sputum infection. The bronchiectasis seen was widespread and severe, particularly in Maori and Pacific Island children. The kappa coefficient for intraobserver agreement was better than that for interobserver agreement. Comparisons between HRCT scan and lung function parameters showed that the strongest relationships were between forced expiratory volume in 1 sec (FEV(1)) and forced expiratory flow between 25-75% of forced vital capacity (FEF(25-75)) with the extent of bronchiectasis, bronchial wall thickening, and air trapping. Children with digital clubbing and chest deformity showed significantly higher scores for extent of bronchiectasis, bronchial wall dilatation and thickness, and overall computed tomography (CT) score. No relationship was demonstrated between chronic sputum infection and CT score. The HRCT score demonstrated a stronger correlation between the extent and severity of bronchiectasis, and spirometry values, than the chest X-ray score. In conclusion, pediatric non-CF bronchiectasis in Auckland is extensive and severe. The good intraobserver ratings mean that consistency of scoring is possible on repeated scans. This study cannot comment on the relationships of CT and less severe disease.

Adolescent↗

PubMed2003

Paediatric bronchiectasis in the twenty-first century: experience of a tertiary children's hospital in New Zealand.

OBJECTIVE: Despite its decline in developed countries, bronchiectasis appeared to be a common diagnosis in Auckland, New Zealand children. The aims of this study were: to document the number of children in Auckland with bronchiectasis, their severity, clinical characteristics and possible aetiologies; to assess whether there was a relationship between ethnicity and poverty; and to estimate a crude bronchiectasis prevalence rate for New Zealand. METHODS: A retrospective review of the case histories of all children attending a tertiary children's hospital in Auckland with bronchiectasis diagnosed by high-resolution chest computed tomography (CT) scan, during the period 1998-2000 was undertaken. Data collected included patient demographics, number of hospitalizations pre- and post-diagnosis, lung function tests, radiology and investigations. The New Zealand deprivation 1996 index was applied to the data to obtain a measure of socio-economic status. RESULTS: Bronchiectasis was found to be common, with an estimated prevalence of approximately one in 6000 in the Auckland paediatric population. It was disproportionately more common in the Pacific Island and Maori children. In Pacific Island children, bronchiectasis not caused by cystic fibrosis was nearly twice as common in the general population than cystic fibrosis. Socio-economic deprivation and low immunization rates may be significant contributing factors. The bronchiectasis seen was extensive. Ninety-three percent had bilateral disease and 64% had involvement of four or more lobes on chest CT scan. A wide range of comorbidities and underlying aetiologies were evident. CONCLUSIONS: Paediatric bronchiectasis in Auckland, New Zealand, is common but underresourced. Only the most severe cases are being recognized, providing a significant challenge for paediatric health professionals.

Administration, Inhalation↗

PubMed2001

Variability in carbon isotopic fractionation during biodegradation of chlorinated ethenes: implications for field applications.

Stable carbon isotopic analysis has the potential to assess biodegradation of chlorinated ethenes. Significant isotopic shifts, which can be described by Rayleigh enrichment factors, have been observed for the biodegradation of trichloroethlyene (TCE), cis-dichloroethylene (cDCE), and vinyl chloride (VC). However, until this time, no systematic investigation of isotopic fractionation during perchloroethylene (PCE) degradation has been undertaken. In addition, there has been no comparison of isotopic fractionation by different microbial consortia, nor has there been a comparison of isotopic fractionation by consortia generated from the same source, but growing under different conditions. This study characterized carbon isotopic fractionation during reductive dechlorination of the chlorinated ethenes, PCE in particular, for microbial consortia from two different sources growing under different environmental conditions in order to assess the extent to which different microbial consortia result in different fractionation factors. Rayleigh enrichment factors of -13.8@1000, -20.4@1000, and -22.4@1000 were observed for TCE, cDCE, and VC, respectively, for dechlorination by the KB-1 consortium. In contrast, isotopic fractionation during reductive dechlorination of perchloroethylene (PCE) could not always be approximated by a Rayleigh model. Dechlorination by one consortium followed Rayleigh behavior (epsilon = -5.2), while a systematic change in the enrichment factor was observed over the course of PCE degradation by two other consortia. Comparison of all reported enrichment factors for reductive dechlorination of the chlorinated ethenes shows significant variation between experiments. Despite this variability, these results demonstrate that carbon isotopic analysis can provide qualitative evidence of the occurrence and relative extent of microbial reductive dechlorination of the chlorinated ethenes.

Biodegradation, Environmental↗

PubMed2000

pGreen: a versatile and flexible binary Ti vector for Agrobacterium-mediated plant transformation.

Binary Ti vectors are the plasmid vectors of choice in Agrobacterium-mediated plant transformation protocols. The pGreen series of binary Ti vectors are configured for ease-of-use and to meet the demands of a wide range of transformation procedures for many plant species. This plasmid system allows any arrangement of selectable marker and reporter gene at the right and left T-DNA borders without compromising the choice of restriction sites for cloning, since the pGreen cloning sites are based on the well-known pBluescript general vector plasmids. Its size and copy number in Escherichia coli offers increased efficiencies in routine in vitro recombination procedures. pGreen can replicate in Agrobacterium only if another plasmid, pSoup, is co-resident in the same strain. pSoup provides replication functions in trans for pGreen. The removal of RepA and Mob functions has enabled the size of pGreen to be kept to a minimum. Versions of pGreen have been used to transform several plant species with the same efficiencies as other binary Ti vectors. Information on the pGreen plasmid system is supplemented by an Internet site (http://www.pgreen.ac.uk) through which comprehensive information, protocols, order forms and lists of different pGreen marker gene permutations can be found.

Agrobacterium tumefaciens↗

PubMed2000

A case of vaccine-associated paralytic poliomyelitis.

Vaccine-associated paralytic poliomyelitis (VAPP) is a very rare complication of oral polio vaccine (OPV), seen predominantly with first exposure to OPV. Reversion of vaccine strain poliovirus to a more neurovirulent strain of the virus is thought to be necessary for paralytic disease to occur. Vaccine-associated poliomyelitis can occur in either recipients of the vaccine or in susceptible contacts. We describe an episode of VAPP in an infant in whom paralysis became evident at age 124 days, 14 days after administration of the second dose of OPV vaccine. The second dose of diphtheria-tetanus-pertussis- Haemophilus (DTPH) type-b vaccine had been given at the time of OPV administration, and the hepatitis B vaccine had been administered in the opposite leg. Paralysis was localized to the limb in which the DTPH had been injected.

Electromyography↗

PubMed2000

Anaerobic toluene activation by benzylsuccinate synthase in a highly enriched methanogenic culture.

Permeabilized cells of a highly enriched, toluene-mineralizing, methanogenic culture catalyzed the addition of toluene to fumarate to form benzylsuccinate under anaerobic conditions. The specific in vitro rate of benzylsuccinate formation was >85% of the specific in vivo rate of toluene consumption. This is the first report of benzylsuccinate synthase activity in a methanogenic culture; the activity has previously been reported to occur in denitrifying, sulfate-reducing, and anoxygenic phototrophic bacteria.

Anaerobiosis↗

PubMed2000

Plasma cholesteryl ester fatty acid composition, insulin sensitivity, the menopause and hormone replacement therapy.

This study was designed to determine the effect of menopause and hormone replacement therapy (HRT) on plasma cholesteryl ester fatty acid (CEFA) composition and insulin sensitivity and the relationships between these variables in perimenopausal women (aged 40-55 years) including 49 who were premenopausal and 32 who were postmenopausal. Plasma cholesteryl ester proportions of dihomo-gamma-linolenic acid (20:3 n-6) were correlated significantly with insulin sensitivity index (r=-0.319, P=0.005), fasting serum insulin levels (r=0.230, P=0.038), body mass index (r=0.242, P=0.03) and per cent body fat (r=0.329, P=0.003) in perimenopausal women (n=81). Similar associations were observed in premenopausal women. Regression analysis suggested the relationships between 20:3 n-6 proportions and indices of insulin action may be partly mediated by levels of adiposity. In postmenopausal women, 6 months of HRT significantly (P=0.008) increased the ratio of arachidonic acid (20:4 n-6) to linoleic acid (18:2 n-6), which is an indicator of activity in the pathway of 20:4 n-6 synthesis, compared with placebo. These findings suggest that the type of fat in the diet indicated by plasma CEFA composition is linked to adiposity and insulin action. They also suggest that in postmenopausal women, HRT may increase the synthesis of 20:4 n-6, which is the precursor for eicosanoids with important cardiovascular functions.

Adult↗

PubMed1999

Anaerobic benzene biodegradation linked to nitrate reduction.

Benzene oxidation to carbon dioxide linked to nitrate reduction was observed in enrichment cultures developed from soil and groundwater microcosms. Benzene biodegradation occurred concurrently with nitrate reduction at a constant ratio of 10 mol of nitrate consumed per mol of benzene degraded. Benzene biodegradation linked to nitrate reduction was associated with cell growth; however, the yield, 8.8 g (dry weight) of cells per mol of benzene, was less than 15% of the predicted yield for benzene biodegradation linked to nitrate reduction. In experiments performed with [14C]benzene, approximately 92 to 95% of the label was recovered in 14CO2, while the remaining 5 to 8% was incorporated into the nonvolatile fraction (presumably biomass), which is consistent with the low measured yield. In benzene-degrading cultures, nitrite accumulated stoichiometrically as nitrate was reduced and then was slowly reduced to nitrogen gas. When nitrate was depleted and only nitrite remained, the rate of benzene degradation decreased to almost zero. Based on electron balances, benzene biodegradation appears to be coupled more tightly to nitrate reduction to nitrite than to further reduction of nitrite to nitrogen gas.

Anaerobiosis↗

PubMed1999

Humidification difficulties in two tracheostomized children.

Effective humidification is sometimes difficult to achieve in children when normal mechanisms are bypassed by having a tracheostomy in situ. The humidification options available in the paediatric population are heat and moisture exchangers (HMEs) and heated humidifiers, both of which are reviewed and discussed. In some circumstances the humidification achieved with HMEs is inadequate. We outline the hospital and subsequent home management of two infants, both with tracheostomies in situ, who unsuccessfully trialed HMEs and subsequently achieved effective humidification with heated humidifiers. We propose that heated humidifiers would help more tracheostomized infants who are suffering from similar problems.

Child, Preschool↗

PubMed1999

Plasma cholesterol esterification and transfer, the menopause, and hormone replacement therapy in women.

With the onset of the menopause, plasma lipids and lipoprotein metabolism changes toward a more atherogenic profile that is improved by HRT. To determine whether cholesterol esterification rate (CER) and transfer of cholesteryl esters from high density lipoproteins to apolipoprotein B-containing lipoproteins are affected by menopause and HRT, plasma newly synthesized cholesteryl ester transfer (NCET) activity, CER and plasma lipids, lipoproteins, and apolipoprotein concentrations were measured in perimenopausal women (age range: 40-55 yr), including 49 premenopausal women and 32 postmenopausal women who were subsequently randomized to receive either placebo or 17-beta estradiol/norethisterone for 6 months. Plasma NCET (P = 0.03) and CER (P = 0.008) were significantly higher in postmenopausal women. Plasma low density lipoprotein cholesterol concentration, high density lipoprotein concentration, and body mass index were independent predictors of plasma NCET in premenopausal women, and plasma triglyceride and apolipoprotein B concentrations were corresponding predictors in postmenopausal women. When data were adjusted for plasma triglyceride, plasma NCET activity was no longer significantly different (P = 0.81) between premenopausal and postmenopausal women. Plasma NCET and CER did not change significantly in postmenopausal women during HRT. These data suggest that the determinants of plasma NCET activity after menopause and increased levels of triglyceride-rich lipoprotein acceptors of cholesteryl esters may lead to increased plasma NCET that is not reduced by HRT in postmenopausal women.

Adult↗

PubMed1997

A long-term comparison between enalapril and captopril on insulin sensitivity in normotensive non-insulin dependent diabetic volunteers.

BACKGROUND: There are conflicting reports about the effects of angiotensin converting enzyme inhibitors on insulin sensitivity and glycaemic control. In addition, the chronic effects of ACEI on insulin sensitivity in normotensive but insulin resistant individuals have been controversial. AIM: To determine the long-term effects of low-dose captopril or enalapril on insulin sensitivity and lipid parameters in normotensive non-insulin dependent diabetic volunteers. METHODS: Twenty-eight normotensive non-insulin dependent diabetes mellitus subjects on diet alone or diet plus oral hypoglycaemic agents were randomized in a single-blind cross-over study to receive either captopril (12.5 mg daily) or enalapril (5 mg daily). Initially, captopril was compared with enalapril for 28 days with a 28-day washout period between drug regimens. For the long-term study, the subjects then remained on the second ACEI for a further 11 months. Insulin sensitivity was measured using the isoglycaemic hyperinsulinaemic clamp (insulin infusion rate 20 mIU/kg/min) at the start and completion of each part of the cross-over study and then at 3, 6 and 12 months of drug therapy. Fasting glucose, insulin, HbA1, lipids and lipoproteins were measured at the start of each clamp. RESULTS: No first or second order carry-over effects were demonstrated between the ACEIs. No differences were detected between enalapril and captopril on insulin sensitivity at any of the time points. Statistically significant hypotension was avoided, and at doses used the ACEIs did not modify any parameters of glycaemic control over the 12-month study period. There were no significant alterations in plasma cholesterol, triglycerides, HDL cholesterol or Apo A1 levels during the study. CONCLUSIONS: Long-term low-dose ACEIs (captopril/enalapril) do not modify insulin sensitivity, glycaemic control or lipids in normotensive non-insulin dependent diabetic subjects.

Aged↗

PubMed1995

The effects of increasing doses of enalapril on insulin sensitivity in normotensive non-insulin dependent diabetic subjects.

BACKGROUND: There are conflicting reports about the effects of ACE inhibitors (ACEI) on insulin sensitivity and glycaemic control. Most studies have used a standard high dose of an ACEI but there have been no studies reported to establish whether any changes in glycaemic control or insulin sensitivity associated with ACEI are dose-related. AIM: To examine the effect of increasing doses of enalapril on insulin sensitivity in normotensive non-insulin dependent diabetic subjects. METHODS: The effects of increasing doses of enalapril on insulin sensitivity in ten normotensive non-insulin dependent diabetic subjects were measured, using the hyperinsulinaemic isoglycaemic clamp technique. Following a baseline study, enalapril was commenced at 5 mg daily and increased to 10 mg daily then 20 mg daily at 14 day intervals. Repeat studies were undertaken after 14 days at each dosage. RESULTS: There was a significant dose-related reduction of systolic blood pressure with enalapril. In contrast enalapril at 5-20 mg daily produced no significant changes in insulin mediated glucose uptake (M-value) or insulin sensitivity index (ISI). CONCLUSIONS: These findings indicate that in this insulin resistant population of normotensive non-insulin dependent diabetics, angiotensin converting enzyme inhibition with enalapril has no significant effect on insulin mediated glucose uptake.

Aged↗