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Biomedical subjects

T Ashton

Publications and source records attributed to T Ashton.

At least 19 recordsLinked to original sources
PubMed2005

Effects of dietary carbohydrate on delayed onset muscle soreness and reactive oxygen species after contraction induced muscle damage.

BACKGROUND: Delayed onset muscle soreness (DOMS) occurs after unaccustomed exercise and has been suggested to be attributable to reactive oxygen species (ROS). Previous studies have shown increased ROS after lengthening contractions, attributable to invading phagocytes. Plasma glucose is a vital fuel for phagocytes, therefore carbohydrate (CHO) status before exercise may influence ROS production and DOMS. OBJECTIVE: To examine the effect of pre-exercise CHO status on DOMS, ROS production, and muscle function after contraction induced muscle damage. METHOD: Twelve subjects performed two downhill runs, one after a high CHO diet and one after a low CHO diet. Blood samples were drawn for analysis of malondialdehyde, total glutathione, creatine kinase, non-esterified fatty acids, lactate, glucose, and leucocytes. DOMS and muscle function were assessed daily. RESULTS: The high CHO diet resulted in higher respiratory exchange ratio and lactate concentrations than the low CHO diet before exercise. The low CHO diet resulted in higher non-esterified fatty acid concentrations before exercise. DOMS developed after exercise and remained for up to 96 hours, after both diets. A biphasic response in creatine kinase occurred after both diets at 24 and 96 hours after exercise. Malondialdehyde had increased 72 hours after exercise after both diets, and muscle function was attenuated up to this time. CONCLUSIONS: Downhill running resulted in increased ROS production and ratings of DOMS and secondary increases in muscle damage. CHO status before exercise had no effect.

Adult↗
PubMed2003

Detection of p53 mutations in precancerous gastric tissue.

Intestinal-type gastric cancer is preceded by gastritis and intestinal metaplasia. There is uncertainty regarding the stage at which genetic alterations in the p53 gene occur. Reactive oxygen species (ROS) may participate in the production of mutations and the inactivation of p53 is due to infection by the bacterium Helicobacter pylori. We have investigated whether alterations of the p53 gene can be detected in gastritis and intestinal metaplasia using the restriction site mutation assay. We also assessed the potential contribution of ROS to p53 inactivation using electron spin resonance spectroscopy (ESR) and correlated with the presence of H. pylori. In all, 35% of the gastritis samples and 45% of the intestinal metaplasia samples were found to contain mutations in exons 5-8 of the p53 gene. Electron spin resonance spectroscopy analysis showed a significant increase in free radical levels in gastritis samples compared with normal, intestinal metaplasia and cancer samples, suggesting that free radicals present in gastritis may contribute to p53 mutations. There was no significant difference in free radical levels between the H. pylori-positive and -negative groups. However, a small subpopulation of the H. pylori-negative patients had much higher levels of free radicals. This suggests a more prominent role for other factors in ROS production.

Acute Disease↗
PubMed2003

Lack of benefit of dietary advice to men with angina: results of a controlled trial.

OBJECTIVE: To see whether mortality among men with angina can be reduced by dietary advice. DESIGN: A randomized controlled factorial trial. SETTING: Male patients of general practitioners in south Wales. SUBJECTS: A total of 3114 men under 70 y of age with angina. INTERVENTIONS: Subjects were randomly allocated to four groups: (1) advised to eat two portions of oily fish each week, or to take three fish oil capsules daily; (2) advised to eat more fruit, vegetables and oats; (3) given both the above types of advice; and (4) given no specific dietary advice. Mortality was ascertained after 3-9 y. RESULTS: Compliance was better with the fish advice than with the fruit advice. All-cause mortality was not reduced by either form of advice, and no other effects were attributable to fruit advice. Risk of cardiac death was higher among subjects advised to take oily fish than among those not so advised; the adjusted hazard ratio was 1.26 (95% confidence interval 1.00, 1.58; P=0.047), and even greater for sudden cardiac death (1.54; 95% CI 1.06, 2.23; P=0.025). The excess risk was largely located among the subgroup given fish oil capsules. There was no evidence that it was due to interactions with medication. CONCLUSIONS: Advice to eat more fruit was poorly complied with and had no detectable effect on mortality. Men advised to eat oily fish, and particularly those supplied with fish oil capsules, had a higher risk of cardiac death. This result is unexplained; it may arise from risk compensation or some other effect on patients' or doctors' behaviour.

Angina Pectoris↗
PubMed2002

Cost-effectiveness of palivizumab in New Zealand.

OBJECTIVE: To establish the preterm infant hospitalization risks from respiratory syncytial virus (RSV) in New Zealand and the net cost per hospitalization averted by palivizumab. METHODS: The 437 infants born < 32 weeks' gestation in 1997 and treated at five major neonatal units were identified. Subsequent admissions during the next 2 years for bronchiolitis, pneumonia and croup were tracked, and information collected on RSV tests performed. Data on the length of stay and hospital costs were used to calculate the potential net cost per hospitalization averted associated with the use of palivizumab and the number needed to treat (NNT) to prevent one hospitalization. RESULTS: Estimated RSV readmission risk before 1 year corrected age in infants < 32 weeks' gestation discharged home on oxygen, and those " 28 weeks' gestation, or between 29 and 31 weeks' gestation with or without chronic lung disease was 42%, 23%, 19%, 10% and 8%, respectively. The NNT with palivizumab to prevent one hospitalization ranged from six to 26 across subgroups. Mean (range) net cost per hospitalization averted was 60,000 New Zealand dollars ($28,000-$166,700). In no subgroup would prophylaxis result in net cost saving. Prophylaxis for all NZ infants " 28 weeks' gestation would cost approximately $1,090,000 net and prevent 29 hospitalizations annually, being equivalent to $37,000 net per hospitalization averted, with eight infants treated to prevent one hospitalization. Alternative assumptions about cost and efficacy failed to alter these findings. CONCLUSION: If value is placed on preventing morbidity, the priority groups for palivizumab prophylaxis are preterm infants discharged home on oxygen, followed by preterm infants of 28 weeks' gestation or less.

Antibodies, Monoclonal↗
PubMed2001

The oxidative mechanism of heparin interferes with radical production by glucose and reduces the degree of glycooxidative modifications on human serum albumin.

Among substances which may prove useful in preventing or reducing the progression of glycooxidative modifications of proteins, heparin plays a unique role. To elucidate the mechanism whereby heparin may favourably influence the protein structure during glycation, human serum albumin (HSA) was glycated with both 25 and 50 mM glucose in the absence and presence of 12 microg.mL(-1) low-molecular-mass heparin. Glycation caused: (a) modifications of fluorescence emission and excitation spectra consistent with the covalent attachment of glucose to protein; (b) a significant increase in the esterase activity of HSA on p-nitrophenyl acetate; (c) a reduced susceptibility to tryptic digestion and (d) enhanced formation of high-molecular mass aggregates of HSA. These alterations were accompanied by oxidative reactions, as the EPR spectra showed a clear-cut radical signal, dependent on glucose concentration, further confirmed by measurement of the carbonyl content of HSA, as an indirect proof of oxidative damage. In the presence of heparin all the above alterations, especially at 25 mM glucose, turned out to be antagonized. The effects of heparin were dependent on its specific binding to HSA, which triggered an oxidative mechanism strikingly different from that caused by glucose. In the presence of heparin, only the radical species catalyzed by heparin was detected across all samples of glycated HSA, irrespective of glucose concentration. In addition, at 25 mM glucose, enhancement of the oxidative capacity of heparin was also observed. The results demonstrate that the oxidative mechanism sustained by heparin mediates biological effects that may be beneficial in reducing the extent of glycooxidative damage on HSA.

Dose-Response Relationship, Drug↗
PubMed2001

The rocky road to health reform: some lessons from New Zealand.

Ongoing structural change has been a feature of the New Zealand health system throughout the 1990s. As we enter the new millennium a new government is now embarking upon yet another round of reform. I look back on the past few years and consider what lessons might be learned about the process of health policy-making in New Zealand. They include the need for a clear vision about the goals of health policy, the importance of consulting with key stakeholders at an early stage, the problems of implementing change too speedily, and the need to allow sufficient time for systems to mature before replacing them with new structures.

Health Care Reform↗
PubMed2001

Commercially available folic acid supplements and their compliance with the British Pharmacopoeia test for dissolution.

A recent report suggested that some folic acid preparations available in the United States failed to meet the specifications for dissolution specified by the US Pharmacopoeia (USP), of 70 per cent drug release in the first hour of testing. The Teratology Society recommends that women of childbearing age should take a daily supplement of 400 microg folic acid when they are trying to conceive, to reduce the risk of foetal neural tube defects. The consequence of this failure to meet the USP requirements may be that an inadequate dose of folate may be absorbed and thus the expected level of protection against neural tube defects not afforded. The purpose of the present study was to examine a number of brands of folic acid (400 microg), available commercially in the United Kingdom, for compliance with the British Pharmacopoeia (BP) test for dissolution. Ten tablets (or capsules) from each of 11 brands were tested using dissolution apparatus compliant with BP requirements, using 0.1 M sodium hydroxide as the dissolution medium. The results indicated that four of the brands failed to release 70 per cent of the nominal drug content in the first hour of test and thus did not comply with the test. Two of the seven brands that passed the test went on to release more than 150 per cent of the nominal 400 microg drug content. These results highlight the problems of dose uniformity and the potential health risks of slow dissolution and under-dosing in commercially available folic acid dosage forms.

Absorption↗
PubMed2000

Public purchasing and private priorities for healthcare in New Zealand.

The 1993 Health and Disability Services Act heralded a range of structural reforms in the New Zealand health care system. Despite these reforms considerable resources being spent on convincing consumers of their merits, have failed to gain widespread public approval. This paper examines two key issues that have arisen during the reform process. These are the difficulties associated with trying to set priorities in ways which are effective and politically acceptable, and the relationship between the public and private sectors. Unacknowledged conflicts of interest have helped to undermine the priority setting process. The discussion suggests that it may be increasingly difficult for any government in future to determine the allocation of resources without taking private sector interests and rising public concern into account. It remains to be seen which of these factors is more powerful.

Contract Services↗
PubMed2000

Priority-setting in New Zealand: translating principles into practice.

In May 1998 the New Zealand Health Funding Authority released a discussion paper which proposed a principles-based approach to setting purchasing priorities that incorporates the economic methods of programme budgeting and marginal analysis, and cost-utility analysis. The principles upon which the process was to be based are effectiveness, cost, equity of health outcomes, Maori health and acceptability. This essay describes and critiques issues associated with translating the principles into practice, most particularly the proposed methods for evaluating the effectiveness and measuring the cost of services. It is argued that the proposals make an important contribution towards the development of a method for prioritizing services which challenges our thinking about those services and their goals, and which is systematic, explicit, and transparent. The shift towards 'thinking at the margin' and systematically reviewing the value for money of competing claims on resources is likely to improve the quality of decision-making compared with the status quo. This does not imply that prioritization can, or should, be undertaken by means of any simple formula. Any prioritization process should always be guided by informed judgement. The approach is more appropriate for some services than for others. Key methodological issues that need further consideration include the choice of instrument for measuring health gains, the identification of marginal services, how to combine qualitative and quantitative information, and how to ensure consistency across different levels of decision-making.

Health Care Costs↗
PubMed1999

Electron spin resonance spectroscopy, exercise, and oxidative stress: an ascorbic acid intervention study.

Oxygen free radicals are highly reactive species that are produced in increased quantities during strenuous exercise and can damage critical biological targets such as membrane phospholipids. The present study examined the effect of acute ascorbic acid supplementation on exercise-induced free radical production in healthy subjects. Results demonstrate increases in the intensity of the alpha-phenyl-tert-butylnitrone adduct (0.05 +/- 0.02 preexercise vs. 0.19 +/- 0.03 postexercise, P = 0.002, arbitrary units) together with increased lipid hydroperoxides (1.14 +/- 0.06 micromol/l preexercise vs. 1.62 +/- 0.19 micromol/l postexercise, P = 0.005) and malondialdehyde (0.70 +/- 0.04 micromol/l preexercise vs. 0.80 +/- 0.04 micromol/l postexercise, P = 0.0152) in the control phase. After supplementation with ascorbic acid, there was no significant increase in the electron spin resonance signal intensity (0.02 +/- 0. 01 preexercise vs. 0.04 +/- 0.02 postexercise, arbitrary units), lipid hydroperoxides (1.12 +/- 0.21 micromol/l preexercise vs. 1.12 +/- 0.08 micromol/l postexercise), or malondialdehyde (0.63 +/- 0.07 micromol/l preexercise vs. 0.68 +/- 0.05 micromol/l postexercise). The results indicate that acute ascorbic acid supplementation prevented exercise-induced oxidative stress in these subjects.

Adolescent↗
PubMed1998

Electron spin resonance spectroscopic detection of oxygen-centred radicals in human serum following exhaustive exercise.

Free radicals or oxidants are continuously produced in the body as a consequence of normal energy metabolism. The concentration of free radicals, together with lipid peroxidation, increases in some tissues as a physiological response to exercise - they have also been implicated in a variety of pathologies. The biochemical measurement of free radicals has relied in the main on the indirect assay of oxidative stress by-products. This study presents the first use of electron spin resonance (ESR) spectroscopy in conjunction with the spin-trapping technique, to measure directly the production of radical species in the venous blood of healthy human volunteers pre- and post-exhaustive aerobic exercise. Evidence is also presented of increased lipid peroxidation and total antioxidant capacity post-exercise.

Adolescent↗
PubMed1998

Contracting for health services in New Zealand: a transaction cost analysis.

The splitting of the functions of purchaser and provider in the New Zealand health system in 1993 necessitated the use of explicit contracts between the two parties. This paper examines contracting experiences during the first two years of operation. The study focuses on four services: rest homes, primary care clinics, surgical services, and acute mental health services. The insights of transaction cost economics form the theoretical framework. The objective of this study was to examine whether the transaction costs associated with contracting vary across the four different services, and whether different types of contracts and contractual relationships are emerging as transactors attempt to reduce these costs. Information was collected in a series of 53 interviews with purchasers and providers, together with any relevant documentation. The results suggest that the costs of contracting are indeed greater for some services than for others. Other variables such as the style of negotiations, the type and specificity of contracts and the degree of monitoring also differ across the four services. At this early stage of the reform process, there was little evidence that purchasers and providers were attempting to reduce transaction costs by negotiating more flexible, longer-term, relational contracts. The main benefit from contracting to date has been improved accountability of service providers.

Aged↗
PubMed1998

Cardiac pacing in Canada in 1998: working towards optimal pacing therapy. Canadian Working Group on Cardiac Pacing.

The Canadian Working Group on Cardiac Pacing (CWGCP) was formed in 1996 with the primary goal of promoting optimal pacing therapy in Canada. In 1997, the CWGCP conducted a survey of pacing practices across Canada. Ninety-two of 125 implanting programs (74%) responded. Implant rates vary by province--from 39 per 100,00 population in Ontario to 63 per 100,000 population in Nova Scotia and Prince Edward Island. Variations in regional implant rates persist even after correcting for the age of the population. Physiological pacing was used for 35% of all implants in Canada in 1996/97. There were marked differences across Canada in the mode of pacing selected. In western Canada, 39.5% of pacing systems implanted were physiological compared with 18.2% in Atlantic Canada and 29% in Quebec. There were also differences in follow-up practices. Approximately 40% of centres follow patients with single chamber pacemakers annually, whereas most other centres still follow these patients every six months. Economic constraints, the size of pacing programs and the involvement of committed pacing physicians are factors that may influence the regional differences in cardiac pacing across Canada.

Canada↗
PubMed1997

Health care costs of obesity in New Zealand.

OBJECTIVE: To estimate the costs of health care that are attributable to obesity in New Zealand. METHODS: The 1991 health care costs of non-insulin dependent diabetes, coronary heart disease, hypertension, gallstone disease, post-menopausal breast cancer and colon cancer were estimated and multiplied by the population attributable factor for obesity for each condition. The relative risk estimates were taken from the literature, the obesity prevalence from a 1990 New Zealand survey, and the costs and volumes of services were taken from a variety of sources and covered hospital (inpatient and outpatient) services, general practitioner consultations, pharmaceuticals, laboratory tests and ambulance services. Calculations were conservative and net of goods and services tax. RESULTS: A conservative estimate of the health care costs attributable to obesity for the six conditions was NZ$135 million. This represents about 2.5% of total health care costs which is similar to analyses from other countries. CONCLUSIONS: The health care costs of obesity as estimated are considerable. However, the total cost of overfatness to the New Zealand population is far greater than this because lesser degrees of overfatness, the health care costs of other obesity-related conditions such as arthritis, the costs to individuals of weight-loss programs and the indirect and intangible costs were not included in the analysis. A substantial and wide-ranging public health effort is needed to turn around the increasing prevalence and costs of obesity.

Adult↗
PubMed1995

The purchaser-provider split in New Zealand: the story so far.

In July 1993 some major structural changes were introduced into the New Zealand health system. The main feature was a separation of the purchasing and providing functions that had previously been performed by area health boards. This paper describes the reasons for and nature of the original (1991) proposals, together with changes that have been made subsequently. It discusses the nature of the contracting environment between purchasers and providers, including the integration of primary and secondary funding, the flexibility of contractual arrangements, and the degree of competition. Some information is provided on progress to date, including the impact on quality of services and accountability of providers, as well as some more tangible measures such as changes in throughput, waiting lists, and expenditure since the restructuring took place. The paper concludes that the success or failure of the purchaser-provider split in New Zealand appears to hang crucially on the contractual arrangements which are struck between purchasers and providers. In the longer term, purchasers are likely to encourage the vertical integration of primary and secondary care providers into managed care organisations styled along the lines of health maintenance organisations. Hence the purchaser-provider split may best be viewed as a temporary structure which provides a pathway towards the desired end, that is, more managed and coordinated patient care provided by vertically integrated organisations which were unlikely to emerge under the previous arrangements.

Contract Services↗
PubMed1994

Preventing child pedestrian injury: pedestrian education or traffic calming?

The traditional approach to the prevention of child pedestrian injuries in New Zealand is pedestrian education. However, none of the programs currently being implemented in New Zealand have ever been shown to reduce injury rates. The allocation of scarce resources to pedestrian education must therefore be questioned. In this paper we estimate the number of serious child pedestrian injuries which might be prevented if the resources allocated to pedestrian education were allocated instead to environmental approaches, in particular, to traffic calming. It is estimated that approximately 18 hospitalisations of child pedestrians could be prevented each year under this alternative resource allocation, disregarding any other benefits of traffic calming. These results emphasise the need to consider the potential sacrifices involved in the allocation of scarce resources to child pedestrian education.

Accidents, Traffic↗