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G Mills

Publications and source records attributed to G Mills.

At least 19 recordsLinked to original sources
PubMed2006

Meta-analysis of the relative sensitivity of semi-natural vegetation species to ozone.

This study identified 83 species from existing publications suitable for inclusion in a database of sensitivity of species to ozone (OZOVEG database). An index, the relative sensitivity to ozone, was calculated for each species based on changes in biomass in order to test for species traits associated with ozone sensitivity. Meta-analysis of the ozone sensitivity data showed a wide inter-specific range in response to ozone. Some relationships in comparison to plant physiological and ecological characteristics were identified. Plants of the therophyte lifeform were particularly sensitive to ozone. Species with higher mature leaf N concentration were more sensitive to ozone than those with lower leaf N concentration. Some relationships between relative sensitivity to ozone and Ellenberg habitat requirements were also identified. In contrast, no relationships between relative sensitivity to ozone and mature leaf P concentration, Grime's CSR strategy, leaf longevity, flowering season, stomatal density and maximum altitude were found. The relative sensitivity of species and relationships with plant characteristics identified in this study could be used to predict sensitivity to ozone of untested species and communities.

Altitude↗
PubMed2006

Identifying ozone-sensitive communities of (semi-)natural vegetation suitable for mapping exceedance of critical levels.

Using published data on the responses of individual species to ozone, 54 EUNIS (European Nature Information System) level 4 communities with six or more ozone-sensitive species (%OS) and c. 20% or more species tested for ozone sensitivity, were identified as potentially ozone-sensitive. The largest number of these communities (23) was associated with Grasslands, with Heathland, scrub and tundra, and Mires, bogs and fens having the next highest representation at 11 and 8 level 4 communities each respectively. Within the grasslands classification, E4 (Alpine and sub-alpine grasslands), E5 (Woodland fringes and clearings) and E1 (Dry grasslands) were the most sensitive with 68.1, 51.6 and 48.6%OS respectively. It is feasible to map the land-cover for these and other communities at level 2, but it may not be currently possible to map the land-cover for all communities identified to be ozone-sensitive at levels 3 and 4.

Altitude↗
PubMed2006

Radical-induced generation of small silver particles in SPEEK/PVA polymer films and solutions: UV-Vis, EPR, and FT-IR studies.

The present study is centered on the processes involved in the photochemical generation of nanometer-sized Ag particles via illumination at 350 nm of aqueous solutions and cross linked films containing sulfonated poly(ether ether ketone) and poly(vinyl alcohol). Optical and electron paramagnetic resonance experiments, including electron nuclear double resonance data, proved conclusively that the photogenerated chromophore exhibiting a band with lambda(max) = 565 nm is an alpha-hydroxy aromatic (ketyl) radical of the polymeric ketone. This reducing species was produced by illumination of either solutions or films, but the radical lifetime extended from minutes in the fluid phase to hours in the solid. Direct evidence is presented that this long-lived chromophore reduces Ag(I), Cu(II), and Au(III) ions in solution. A rate constant of k = 1.4 x 10(3) M(-)(1) s(-)(1) was obtained for the reduction of Ag(+) by the ketyl radical from the post-irradiation formation of Ag crystallites. FTIR results confirmed that the photoprocess yielding polymeric ketyl radicals involves a reaction between the macromolecules. The photochemical oxidation of the polymeric alcohol, as well as the formation of light-absorbing macromolecular products and polyols, indicates that the sulfonated polyketone experienced transformations similar to those encountered during illumination of the benzophenone/2-propanol system.

Journal Article↗
PubMed2005

Measurement and modelling of air pollution and atmospheric chemistry in the U.K. West Midlands conurbation: overview of the PUMA Consortium project.

The PUMA (Pollution of the Urban Midlands Atmosphere) Consortium project involved intensive measurement campaigns in the Summer of 1999 and Winter of 1999/2000, respectively, in which a wide variety of air pollutants were measured in the UK West Midlands conurbation including detailed speciation of VOCs and major component analysis of aerosol. Measurements of the OH and HO2 free radicals by the FAGE technique demonstrated that winter concentrations of OH were approximately half of those measured during the summer despite a factor of 15 reduction in production through the photolysis of ozone. Detailed box modelling of the fast reaction chemistry revealed the decomposition of Criegee intermediates formed from ozone-alkene reactions to be responsible for the majority of the formation of hydroxyl in both the summer and winter campaigns, in contrast to earlier rural measurements in which ozone photolysis was predominant. The main sinks for hydroxyl are reactions with NO2, alkenes and oxygenates. Concentrations of the more stable hydrocarbons were found to be relatively invariant across the conurbation, but the impacts of photochemistry were evident through analyses of formaldehyde which showed the majority to be photochemical in origin as opposed to emitted from road traffic. Measurements on the upwind and downwind boundaries of the conurbation revealed substantial enhancements in NOx as a result of emissions within the conurbation, especially during westerly winds which carried relatively clean air. Using calcium as a tracer for crustal particles, it proved possible to reconstruct aerosol mass from the major chemical components with a fairly high degree of success. The organic to elemental carbon ratios showed a far greater influence of photochemistry in summer than winter, presumably resulting mainly from the greater availability of biogenic precursors during the summer campaign. Two urban airshed models were developed and applied to the conurbation, one Eulerian, the other Lagrangian. Both were able to give a good simulation of concentrations of both primary and secondary pollutants at urban background locations.

Acetone↗
PubMed2005

Sulfonated poly(ether ether ketone)/poly(vinyl alcohol) sensitizing system for solution photogeneration of small Ag, Au, and Cu crystallites.

Illumination of air-free aqueous solutions containing sulfonated poly(ether ether ketone) and poly(vinyl alcohol) with 350 nm light results in benzophenone ketyl radicals of the polyketone. The polymer radicals form with a quantum yield 0.02 and decay with a second-order rate constant 6 orders of magnitude lower than that of typical alpha-hydroxy radicals. Evidence is presented that the polymeric benzophenone ketyl radicals reduce Ag+, Cu2+, and AuCl4- to metal particles of nanometer dimensions. Decreases in the reduction rates with increasing Ag(I), Cu(II), and Au(III) concentrations are explained using a kinetic model in which the metal ions quench the excited state of the polymeric benzophenone groups, which forms the macromolecular radicals. Quenching is fastest for Ag+, whereas Cu2+ and AuCl4- exhibit similar rate constants. Particle formation becomes more complex as the number of equivalents needed to reduce the metal ions increases; the Au(III) system is an extreme case where the radical reactions operate in parallel with secondary light-initiated and thermal reduction channels. For each metal ion, the polymer-initiated photoreactions produce crystallites possessing distinct properties, such as a very strong plasmon in the Ag case or the narrow size distribution exhibited by Au particles.

Journal Article↗
PubMed2004

Polymer-initiated photogeneration of silver nanoparticles in SPEEK/PVA films: direct metal photopatterning.

Cross-linking of sulfonated poly(ether-ether)ketone-poly(vinyl alcohol) (SPEEK-PVA) materials yields flexible polymer films, possessing high light-sensitivity and ion-exchange capabilities. Adsorbed Ag+ ions are photoreduced in the film under illumination (lambda = 350 nm), leading to metal nanoparticle formation in places where the film has been exposed to the light. Nanoparticles form via reduction of Ag+ by the polymeric alcohol radicals, generated in the system as a result of photochemical H-abstraction from PVA molecules by the excited carbonyl triplet state of SPEEK. Use of the films for direct metal photopatterning is demonstrated.

Journal Article↗
PubMed2004

Community-acquired pneumonia: influence of management practices on length of hospital stay.

AIMS: To identify variation in the management of -community-acquired pneumonia between two New Zealand hospitals and the factors that may account for any differences. METHODS: A 12-month, prospective two-centre study was conducted. Between July 1999 and July 2000, 474 adult patients with community-acquired pneumonia were enrolled: 304 in Christchurch Hospital and 170 in Waikato Hospital. The patients were similar in age, sex, prior antibiotic use and comorbidity. There was no significant difference in the clinical outcomes for the patients at the two centres. RESULTS: The mean duration of i.v. antibiotic therapy was 1.7 versus 3.0 days (P < 0.001) and length of stay (LOS) was 3.0 versus 5.9 days (P < 0.001) for Waikato and Christchurch Hospitals, respectively. Using multivariate analysis, we could account for 61% of the observed variation in LOS. Duration of i.v. antibiotic therapy independently accounted for 16% of variation in LOS compared with age (2%), chronic obstructive pulmonary disease, duration of fever, intensive care unit admission and centre of admission (all <1%). For the duration of i.v. antibiotics, centre of admission, largely reflecting clinician practice at each centre, independently accounted for 13% of variation, compared with duration of fever (5%), admission to the Intensive Care Unit (4%), Pneumonia Severity Index score (3%) and bacteraemia (3%). CONCLUSION: Of the identifiable factors, variations in clinician behaviour outweighed the influence of patient factors on the duration of i.v. antibiotic therapy, which in turn was the major determinant of LOS for patients hospitalised with community-acquired pneumonia. An early switch from i.v. to oral antibiotic therapy in conjunction with early discharge planning may significantly reduce LOS without compromising patient outcomes.

Aged↗
PubMed2003

Current research and treatment for epithelial ovarian cancer. A Position Paper from the Helene Harris Memorial Trust.

In March 2003, an international mulltidisciplinary group of scientists and clinicians with a specific interest in ovarian cancer met for 4 days to discuss research into and treatment of this challenging disease. Under the headings of molecular genetics, molecular biology, the biology of ovarian cancer, old therapies, new targets and the early detection of the disease, this Position Paper summarises the presentations and discussion from the 9th Biennial Helene Harris Memorial Trust Forum on Ovarian Cancer. In particular, we highlight the potential of international collaborations in translating laboratory science into useful clinical interventions.

Antineoplastic Agents↗
PubMed2001

Community-acquired pneumonia in Christchurch and Waikato 1999-2000: microbiology and epidemiology.

AIMS: To prospectively record current epidemiology and microbiology of community-acquired pneumonia in two New Zealand centres. METHODS: Between July 1999 and 2000 all adults admitted to Christchurch and Waikato Hospitals with community-acquired pneumonia were screened for study inclusion. All those enrolled had their medical history, clinical variables, inpatient management and clinical outcomes recorded and standardised microbial diagnostic testing carried out. RESULTS: 474 participants were enrolled with a mean age of 64 years and a microbial diagnosis was made in 197 cases (42%). Streptococcus pneumoniae (14%), Haemophilus influenzae (10%) and Influenza A virus (7%), Legionella spp (4%) and Mycoplasma pneumoniae (3%) were the most commonly isolated organisms. An 'atypical' organism was diagnosed in 8% of cases compared to 30% and 23% in previous Christchurch and Waikato studies respectively. Fourteen of the 67 S pneumoniae isolates (21%) had reduced susceptibility to penicillin, all with a MIC < or = 2 microg/mL, a level of reduced susceptibility not associated with worse patient outcomes. Clinical outcome included a mean hospital stay of 6.7 days and a 6 week mortality of 6%. CONCLUSION: Although S pneumoniae was the most commonly isolated organism in this study there have been significant changes in the prevalence of atypical organisms since previous surveys. Ongoing surveillance of antibiotic resistance and variations in the prevalence of organisms causing community-acquired pneumonia is required to guide clinicians' empiric antibiotic use.

Adult↗
PubMed2001

Zoledronic acid is superior to pamidronate in the treatment of hypercalcemia of malignancy: a pooled analysis of two randomized, controlled clinical trials.

PURPOSE: Two identical, concurrent, parallel, multicenter, randomized, double-blind, double-dummy trials were conducted to compare the efficacy and safety of zoledronic acid and pamidronate for treating hypercalcemia of malignancy (HCM). PATIENTS AND METHODS: Patients with moderate to severe HCM (corrected serum calcium [CSC] > or = 3.00 mmol/L [12.0 mg/dL]) were treated with a single dose of zoledronic acid (4 or 8 mg) via 5-minute infusion or pamidronate (90 mg) via 2-hour infusion. A protocol-specified pooled analysis of the two parallel trials was performed. Clinical end points included rate of complete response by day 10, response duration, and time to relapse. RESULTS: Two hundred eighty-seven patients were randomized and evaluated for safety; 275 were evaluated for efficacy. Both doses of zoledronic acid were superior to pamidronate in the treatment of HCM. The complete response rates by day 10 were 88.4% (P = .002), 86.7% (P = .015), and 69.7% for zoledronic acid 4 mg and 8 mg and pamidronate 90 mg, respectively. Normalization of CSC occurred by day 4 in approximately 50% of patients treated with zoledronic acid and in only 33.3% of the pamidronate-treated patients. The median duration of complete response favored zoledronic acid 4 and 8 mg over pamidronate 90 mg with response durations of 32, 43, and 18 days, respectively. CONCLUSION: Zoledronic acid is superior to pamidronate; 4 mg is the dose recommended for initial treatment of HCM and 8 mg for relapsed or refractory hypercalcemia.

Adult↗
PubMed2000

An approach to analysis of large-scale correlations between genome changes and clinical endpoints in ovarian cancer.

This report describes analyses of associations of genome copy number abnormalities in ovarian cancers with clinical features using genome-wide graphical and analytical procedures. These studies show that tumor grade is a better indicator of the extent of genomic progression than stage, that loss of chromosome 4 occurs preferentially in high-grade tumors, and that gains of 3q26-qter, 8q24-qter, and 20q13-qter occur frequently in low-grade and low-stage tumors and thus may be early events in ovarian cancer development. In addition, loss of chromosome 16q24 and a total number of independent genome copy number aberrations >7 are associated with reduced survival duration. The association of loss of 16q24 (D16S3026) with decreased survival duration was confirmed by quantitative PCR. Regions that frequently are abnormal and associated with altered survival duration are strong candidates for higher resolution analysis and gene discovery and may be useful markers for prediction of clinical outcome.

Chromosome Aberrations↗
PubMed2000

Phenological weighting of ozone exposures in the calculation of critical levels for wheat, bean and plantain.

This paper presents phenological weighting factors to be applied to AOT40 (accumulated ozone exposure above a threshold of 40 nl l(-1)) ozone exposure-response relationships for crops at different growth stages. The quantification of such factors represents a step-forward in the derivation of Level II critical levels for ozone. The weighting factors presented are derived from published literature on the sensitivity of wheat (Triticum aestivum), bean (Phaseolus vulgaris) and plantain (Plantago major) to ozone at different growth stages. Weighting functions were calculated using either multiple linear regression or the reciprocal residual mean square (RMS(-1)). The resulting weights were transformed into multiplication factors to be applied to the monthly AOT40 during the 3-month assessment period of critical level exceedance. Interspecific differences were too large to allow for the development of a unified weighting function for the three species considered. For wheat grain yield, the derived multiplication factors varied by almost four-fold (0.40, 1.06, 1.54), while those for bean pod yield varied by only about 25% (0.85, 1.01, 1.14). The available data for plantain were restricted to short-term studies conducted under controlled conditions. These data were not suitable for the derivation of weighting factors comparable to those derived for bean and wheat. Based on known differences in wheat development and phenology across Europe, the need for a geographic differentiation of the time period for the calculation of the critical level exceedances is also discussed and examples provided of the adoption of the derived weightings in the mapping of critical level exceedances. Differences between critical level exceedance maps using weighted and unweighted AOT40 calculations are discussed.

Journal Article↗
PubMed2000

Development of a multi-factor model for predicting the effects of ambient ozone on the biomass of white clover.

Results are presented from the UN/ECE ICP Vegetation (International Cooperative Programme on effects of air pollution on natural vegetation and crops) experiments in which ozone(O(3))-resistant (NC-R) and -sensitive (NC-S) clones of white clover (Trifolium repens cv. Regal) were exposed to ambient O(3) episodes at 14 sites in eight European countries in 1996, 1997 and 1998. The plants were grown according to a standard protocol, and the forage was harvested every 28 days for 4-5 months per year by excision 7 cm above the soil surface. Biomass ratio (NC-S/NC-R) was related to the climatic and pollutant conditions at each site using multiple linear regression (MLR) and artificial neural networks (ANNs). Twenty-one input parameters [e.g. AOT40, 7-h mean O(3) concentration, daylight vapour pressure deficit (VPD), daily maximum temperature] were considered individually and in combination with the aim of developing a model with high r(2) and simple structure that could be used to predict biomass change in white clover. MLR models were generally more complex, and performed less well for unseen data than non-linear ANN models. The ANN model with the best performance had five inputs with an r(2) value of 0.84 for the training data, and 0.71 for previously unseen data. Two inputs to the model described the O(3) conditions (AOT40 and 24-h mean for O(3)), two described temperature (daylight mean and 24-h mean temperature), and the fifth input appeared to be differentiating between semi-urban and rural sites (NO concentration at 17:00). Neither VPD nor harvest interval was an important component of the model. The model predicted that a 5% reduction in biomass ratio was associated with AOT40s in the range 0.9-1.7 ppm x h (microl l(-1) h) accumulated over 28 days, with plants being most sensitive in conditions of low NO(x), medium-range temperature, and high 24-h mean O(3) concentration.

Journal Article↗
PubMed2000

A phase II trial of topotecan in esophageal carcinoma: a Southwest Oncology Group study (SWOG 9339).

BACKGROUND: Chemotherapeutic treatments containing topoisomerase I inhibitors have shown antitumor activity against a number of solid tumors. Responses have been seen in Phase I trials using topotecan in ovarian, lung, and esophageal cancer. A phase II trial using continuous infusion topotecan was completed to assess activity in esophagus cancer. METHODS: Forty-five eligible patients with locally-advanced or metastatic squamous cell carcinoma or adenocarcinoma of the esophagus received a regimen consisting of 24-hour continuous infusion topotecan at 1.5 mg/m2/day on Days 1, 8, 15, 22 (of 42-day cycle). Patients continued on treatment until evidence of disease progression or unacceptable toxicity. RESULTS: Partial response was demonstrated in 1 patient (2% confirmed response rate). Thirty-six patients progressed during the first cycle of treatment. The median survival was 3 months, and the median progression-free survival was 1 month. Toxicity was mild with only one Grade 4 toxicity reported. CONCLUSIONS: This phase II trial indicates no significant anti-neoplastic activity for topotecan administered in the dose and schedule to patients with squamous cell or adenocarcinoma of the esophagus.

Adenocarcinoma↗
PubMed2000

Two new microscopical variants of thermomechanical modulation: scanning thermal expansion microscopy and dynamic localized thermomechanical analysis

We describe two ways in which thermomechanical modulation may be used in conjunction with scanning thermal microscopy, in order to distinguish between different components of an inhomogeneous sample. The sample is subjected to a modulated mechanical stress, and the heating is supplied locally by the probe itself. Scanning thermal expansion microscopy is an imaging mode, in which an imposed localized temperature modulation is used to generate thermal expansion, which in turn produces mechanical strain and gives thermal expansion contrast images. We present results using two types of active thermal probe. For polymer/resin samples, the depth of material contributing to the measured thermal expansion is typically a few micrometres. Under certain conditions we observe a reversal in contrast as the frequency of the temperature modulation is increased. In dynamic localized thermomechanical analysis, the modulated stress is applied directly, and accompanied by a localized temperature change, as used in other forms of localized thermal analysis. The resulting modulated lateral force signals are obtained. The glass transition of polystyrene is detected, and shows a significant variation with frequency. The amplitude or phase signal may be used to obtain image contrast for inhomogeneous samples.

Journal Article↗
PubMed1999

Growth suppression of human ovarian cancer cell lines by the introduction of a p16 gene via a recombinant adenovirus.

OBJECTIVE: The cell cycle regulatory protein p16 (CDKN2/cyclin dependent kinase 4 inhibitor/multiple tumor suppressor-1) causes cell cycle arrest at the G1 checkpoint by inhibiting activity of cyclin D-CDK4 complexes. The purpose of this study is to assess the effect of introduction of the p16 gene into two ovarian cancer cell lines via a recombinant adenoviral vector (Ad5CMV-p16). METHODS: Cells lines used were SKOV3, which has a p16 deletion, and OVCA420, which has normal p16. Transduction efficiency was established by infecting cells with an adenovirus containing the Escherichia coli beta-galactosidase gene (Ad5CMV-beta-gal) at multiplicity of infection from 0 to 1000 and staining for X-gal. Cells were infected with Ad5CMV-p16 and cell growth was assessed by counting cells every other day for up to 7 days. Western blotting was done to assess for p16 expression after infection. Fluorescence-activated cell sorting after staining with propidium iodide was done to assess the effect of p16 on the cell cycle. RESULTS: The SKOV3 cell line was transduced with the adenovirus at a slightly lower MOI than the OVCA420 cell line. Growth of the Ad5CMV-p16-infected cells was suppressed 75-80% by cell count in both cell lines and caused morphologic changes of the cells consistent with apoptosis. The p16 protein expression was seen to increase within 24 h after introduction of the p16 gene. G1 arrest of cells occurred beginning 24 h after introduction of the p16 gene. CONCLUSIONS: These results suggest that Ad5CMV-p16 may be further studied as a potential therapeutic agent for ovarian cancer as introduction of the p16 gene into ovarian cancer cell lines causes a G1 arrest and attenuation of growth, regardless of the endogenous p16 status of the cells.

Adenoviruses, Human↗