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Biomedical subjects

S Petrou

Publications and source records attributed to S Petrou.

At least 37 records · Page 2Linked to original sources
PubMed2000

Cost-effectiveness of a delayed pushing policy for patients with epidural anesthesia. The PEOPLE (Pushing Early or Pushing Late with Epidural) Study Group.

OBJECTIVE: The purpose of this study was to estimate the economic efficiency of a policy of delayed pushing for nulliparous women who have full dilatation while they are under epidural anesthesia. STUDY DESIGN: A cost-effectiveness evaluation was based on a randomized controlled trial. Resource use and clinical effectiveness data were collected for 1862 women who were randomly allocated to either a delayed pushing group (n = 936) or an early pushing group (n = 926). Costs (in 1997 Canadian dollars) were collected for each item of resource use. Sensitivity analysis was used to examine the robustness of the main results. RESULTS: Delayed pushing was effective at reducing the number of difficult deliveries (relative risk, 0.79; 95% confidence interval, 0.66 to 0.95). The mean cost of intrapartum care was significantly higher in the delayed pushing group ($625.86 vs $557.64; P <.0005). There were no significant differences in mean costs of postnatal care ($2146.67 vs $2133.54; P =.871) or total hospital care ($2772.53 vs $2691.18; P =.324). The incremental cost per difficult delivery prevented was estimated at $1743.06. The incremental cost-effectiveness ratio remained fairly robust with variations in the values of key parameters incorporated into the sensitivity analysis. CONCLUSIONS: The results of this economic evaluation should inform decision makers determining whether to advocate a policy of delayed pushing for nulliparous women who have full dilatation while they are under epidural anesthesia.

Anesthesia, Epidural↗
PubMed2000

Recent economic evaluations of antenatal screening: a systematic review and critique.

A systematic review of recent economic evaluations of antenatal screening was conducted. Relevant studies were identified from a number of sources including computerised databases, bibliographies of economic evaluations, and searches of unpublished manuscripts. Each study identified by the literature searches was categorised on the basis of its title and abstract. Studies considered relevant to the systematic review were obtained from libraries. The methodology, results, and policy implications of studies categorised as economic evaluations upon full review were documented. A total of 566 studies were identified by the literature searches, 41 of which were categorised as economic evaluations upon full review. The economic evaluations covered a range of antenatal screening practices, aimed mainly at the prevention of infectious diseases and fetal anomalies. The review highlighted the poor methodological quality of the bulk of economic evaluations of antenatal screening. The study design, data collection methods, and analysis and interpretation of results frequently violated methodological guidelines adopted by health economists. The review also highlighted the narrow definition of benefits adopted by this body of literature, with most studies reporting outcomes in terms of cases detected, cases of particular disorders prevented or, most often, costs averted. The conclusions arrived at differed by area of antenatal screening. There appeared to be clear economic arguments in favour of some forms of antenatal screening, for example, triple test screening for Down's syndrome. Other economic evaluations pertained to specific locations, which suggests that the results may not necessarily be generalizable to different settings. For all areas of antenatal screening, an updating of published economic evaluations may be required to account for evolving economic, epidemiological, and clinical effectiveness evidence.

Costs and Cost Analysis↗
PubMed2000

A review of alternative approaches to healthcare resource allocation.

The resources available for healthcare are limited compared with demand, if not need, and all healthcare systems, regardless of their financing and organisation, employ mechanisms to ration or prioritise finite healthcare resources. This paper reviews alternative approaches that can be used to allocate healthcare resources. It discusses the problems encountered when allocating healthcare resources according to free market principles. It then proceeds to discuss the advantages and disadvantages of alternative resource allocation approaches that can be applied to public health systems. These include: (i) approaches based on the concept of meeting the needs of the population to maximising its capacity to benefit from interventions; (ii) economic approaches that identify the most efficient allocation of resources with the view of maximising health benefits or other measures of social welfare; (iii) approaches that seek to ration healthcare by age; and (iv) approaches that resolve resource allocation disputes through debate and bargaining. At present, there appears to be no consensus about the relative importance of the potentially conflicting principles that can be used to guide resource allocation decisions. It is concluded that whatever shape tomorrow's health service takes, the requirement to make equitable and efficient use of finite healthcare resources will remain.

Health Care Rationing↗
PubMed2000

[Multicenter randomized trial of amnioinfusion].

Meconium staining of the amniotic fluid in labor is a frequent problem that is associated with an increase in the risk of neonatal and maternal morbidity. Amnioinfusion is a simple technique that is designed to prevent neonatal and maternal morbidity associated with meconium. Preliminary studies indicate that amnioinfusion is a promising approach to the prevention of such complications of labor. However, further research is required. The primary objective of this multi-centre randomized controlled study is to determine if amnioinfusion for thick meconium stained amniotic fluid results in a reduction in perinatal death or moderate to severe meconium aspiration syndrome. We will also assess the effects of amnioinfusion on other indicators of neonatal morbidity and on cesarean section. The study includes an evaluation of womens views on their childbirth experience and an economic evaluation of a policy of amnioinfusion The study will be achieved with the collaboration of approximately 50 obstetrical centres from across Canada, US, Europe, South America and South Africa. This multicentre trial will provide urgently needed information on the efficacy and effectiveness of amniofusion for the indication of meconium stained amniotic fluid.

Amniotic Fluid↗
PubMed1999

Demograghic and socio-economic determinants of community and hospital services costs for people with HIV/AIDS in London.

We examined the influence of demographic, social and economic background of people with HIV/AIDS in London on total community and hospital services costs. This was a retrospective study of community and hospital service use, needs and costs based on structured questionnaires administered by trained interviewers and costing information obtained from the service purchasers and providers, based on two Genito-urinary Medicine clinics in London: the Jefferiss Wing at St. Mary's Hospital and Patric Clements at the Central Middlesex Hospital, London, England. The subjects were 225 HIV infected patients (105 asymptomatic, 59 symptomatic non-AIDS and 61 AIDS). We found that over and above well established determinants of health care costs for HIV infected people such as disease stage and transmission category, social and economic factors such as employment and support of a living-in partner significantly reduced community services costs. Private health insurance had a similar effect, though only a small proportion of HIV people had such cover. The cost of community services for HIV infected non-European Union nationals, mainly of African origin, was one quarter that for the European Union nationals. Community services costs were highest for heterosexually infected women and lowest for heterosexually infected men after adjusting for other factors. Hospital services costs were significantly higher for HIV infected people lacking educational qualifications and employment. We conclude that access to community care for HIV infected non-EU nationals appears to be very poor as the cost of their community services was one quarter that for the EU nationals after adjusting for the effects of transmission category, disease stage, living with a partner, employment and having a private health insurance. Additional incentives for informal care for HIV infected people could be a cost-effective way to improve their community health service provisions.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Ca(2+) influx inhibits voltage-dependent and augments Ca(2+)-dependent K(+) currents in arterial myocytes.

These experiments were performed to determine the effects of reducing Ca(2+) influx (Ca(in)) on K(+) currents (I(K)) in myocytes from rat small mesenteric arteries by 1) adding external Cd(2+) or 2) lowering external Ca(2+) to 0.2 mM. When measured from a holding potential (HP) of -20 mV (I(K20)), decreasing Ca(in) decreased I(K) at voltages where it was active (>0 mV). When measured from a HP of -60 mV (I(K60)), decreasing Ca(in) increased I(K) at voltages between -30 and +20 mV but decreased I(K) at voltages above +40 mV. Difference currents (DeltaI(K)) were determined by digital subtraction of currents recorded under control conditions from those obtained when Ca(in) was decreased. At test voltages up to 0 mV, DeltaI(K60) exhibited kinetics similar to control I(K60), with rapid activation to a peak followed by slow inactivation. At 0 mV, peak DeltaI(K60) averaged 75 +/- 13 pA (n = 8) with Cd(2+) and 120 +/- 20 pA (n = 9) with low Ca(2+) concentration. At test voltages from 0 to +60 mV, DeltaI(K60) always had an early positive peak phase, but its apparent "inactivation" increased with voltage and its steady value became negative above +20 mV. At +60 mV, the initial peak DeltaI(K60) averaged 115 +/- 18 pA with Cd(2+) and 187 +/- 34 pA with low Ca(2+). With 10 mM pipette BAPTA, Cd(2+) produced a small inhibition of I(K20) but still increased I(K60) between -30 and +10 mV. In Ca(2+)-free external solution, Cd(2+) only decreased both I(K20) and I(K60). In the presence of iberiotoxin (100 nM) to inhibit Ca(2+)-activated K(+) channels (K(Ca)), Cd(2+) increased I(K60) at all voltages positive to -30 mV while BAY K 8644 (1 microM) decreased I(K60). These results suggest that Ca(in), through L-type Ca(2+) channels and perhaps other pathways, increases K(Ca) (i.e., I(K20)) and decreases voltage-dependent K(+) currents in this tissue. This effect could contribute to membrane depolarization and force maintenance.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1999

Chronic treatment with finasteride daily does not affect spermatogenesis or semen production in young men.

PURPOSE: Finasteride, an oral type 2, 5alpha-reductase inhibitor, is used in 1 mg. daily doses for the treatment of male pattern hair loss. A dose of 5 mg. finasteride daily reduces ejaculate volume by approximately 25%, and reduces prostate volume by approximately 20% and serum prostate specific antigen (PSA) by approximately 50% in men with benign prostatic hyperplasia. To our knowledge no data exist on the effect of 1 mg. finasteride daily on ejaculate volume or other semen parameters, or on the prostate in young men. Therefore, we studied the potential effect and reversibility of effect of 1 mg. finasteride daily on spermatogenesis, semen production, the prostate and serum PSA in young men. MATERIALS AND METHODS: In this double-blind, placebo controlled multicenter study 181 men 19 to 41 years old were randomized to receive 1 mg. finasteride or placebo for 48 weeks followed by a 60-week off-drug period. Of the 181 men 79 were included in a subset for the collection and analysis of sequential semen samples. RESULTS: There were no significant effects of 1 mg. finasteride on sperm concentration, total sperm per ejaculate, sperm motility or morphology. Ejaculate volume in subjects on finasteride decreased 0.3 ml. (-11%) compared to a decrease of 0.2 ml. (-8%) for placebo, with a median between treatment group difference of -0.03 ml. (1%, 90% confidence interval -10.4 to 13.1, p = 0.915). There were significant but small decreases in prostate volume (-2.6%) and serum PSA (-0.2 ng./ml.) in the finasteride group, which reversed on discontinuation of the drug. CONCLUSIONS: Treatment with 1 mg. finasteride daily for 48 weeks did not affect spermatogenesis or semen production in young men. The effects of 1 mg. finasteride daily on prostate volume and serum PSA in young men without benign prostatic hyperplasia were small and reversible on discontinuation of the drug.

Adult↗
PubMed1997

P2X7 purinoceptor expression in Xenopus oocytes is not sufficient to produce a pore-forming P2Z-like phenotype.

The purinergic rP2X7 receptor expressed in a number of heterologous systems not only functions as a cation channel but also gives rise to a P2Z-like response, i.e. a reversible membrane permeabilization that allows the passage of molecules with molecular masses of > or = 300 Da. We investigated the properties of rP2X7 receptors expressed in Xenopus oocytes. In two-electrode voltage-clamp experiments, ATP or BzATP caused inward currents that were abolished or greatly diminished when NMDG+ or choline replaced Na+ as the principal external cation. In fluorescent dye experiments, BzATP application did not result in entry of the fluorophore YO-PRO-1(2+). Thus, rP2X7 expression in Xenopus oocytes does not by itself give rise to the pore-forming P2Z phenotype, suggesting that ancillary factors are involved.

Adenosine Triphosphate↗
PubMed1996

Community service needs of people with HIV infection in London.

The objectives of this study were to describe the expressed needs for community services of HIV-infected individuals by disease stage, gender and transmission category and the barriers which prevent the receipt of such services. Structured interviewer-administered questionnaires concerning a 6-month retrospective period were used to obtain information on need for community services and problems which prevented the receipt of services. The study sample included 70 homosexual men with asymptomatic HIV disease, 42 homosexual men with symptomatic non-AIDS, 53 homosexual men with AIDS, 23 heterosexual men, 29 heterosexual women, 9 male and 9 female injecting drug users. The main outcome measures were the extent to which needs for community services were met and person/service combinations for which problems or barriers prevented the receipt of community services. On average, subjects expressed a need for 10 categories of community services over the 6-month period: homosexuals expressed a mean of 10, heterosexuals 10, injecting drug users 11, subjects with asymptomatic HIV infection 9, subjects with symptomatic non-AIDS 11, subjects with AIDS 13, men 9 and women 14. A total of 58% of community service needs were always met, 6% were rarely not met, 16% were sometimes not met, 6% were often not met and 14% were not met at all. The extent to which subjects felt that their needs were met was similar for the different study groups, but the needs of women were met somewhat less frequently than those of men. Similarly, people with AIDS felt that their needs were met slightly less often. Reported levels of unmet need were high for a wide range of services. The most common reason subjects gave for not having received a community service for which they expressed a need was ignorance of where or how to obtain the service. This was mentioned in one-third of all such cases. Anxieties over the competence with which a service would be rendered was mentioned in 13% of cases and long waiting times in 11%. The frequencies of unmet need for many community services were high and often seemed to arise either from a lack of awareness on the part of subjects on how and where services could be obtained or from doubts about the relevance of services offered. Both of these barriers should be surmountable through the provision of better information to patients, extending user involvement in service development and the better co-ordination of service delivery through care management approaches.

Adult↗
PubMed1996

The economic costs of caring for people with HIV infection and AIDS in England and Wales.

The objectives of this study were firstly to estimate total lifetime care costs for an individual with HIV/AIDS, and secondly to estimate the total costs of caring people with HIV infection and AIDS in England and Wales between 1992 and 1997 inclusive. Questionnaires and monthly diaries were used to collate data on healthcare utilisation from patients with HIV infection over a 6-month period. These data were then used to estimate the annual total direct costs of care (stratified by disease stage), total lifetime costs of care, and present and future total national care costs for England and Wales. Costing data were obtained from providers of services throughout Greater London. In total, 235 patients with HIV infection were recruited from 2 clinics in Greater London. All costs were calculated in 1992-93 pounds sterling (pound; 1 pound = $US1.58, December 1995). Annual care costs were estimated at 4515 pounds ($US7134) for a person with asymptomatic HIV disease, 8836 pounds ($US13,961) for a person with symptomatic non-AIDS and 15 268 pounds ($US24,123) for a person with AIDS. Lifetime care costs were estimated at 84,522 pounds ($US133,545) per patient. The total costs of care for England and Wales were forecast to increase from 116,627,400 pounds ($US184,271,300) in 1992 to 162,638,100 pounds ($US256,968,200) in 1997. In conclusion, our study further emphasises the continued shift in hospital services from the inpatient sector to the outpatient sector. The importance of community care and informal care, in terms of the associated direct economic costs, is also highlighted. This emphasises the need for close collaboration between different agencies and strategic coordination of services. Finally, the study forecasts an increase in care costs in England and Wales during the 1990s.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Stretch activation of a toad smooth muscle K+ channel may be mediated by fatty acids.

1. using standard single channel patch clamp techniques we studied the stretch sensitivity of a 20 pS K(+)-selective channel which is activated by fatty acids and found in freshly dissociated smooth muscle cells from the stomach of the toad Bufo marinus. 2. A pulse of suction applied to the back of the patch pipette in order to stretch the membrane resulted in activation of this K+ channel. A train of suction pulses resulted in a gradually increased level of channel activity during each successive pulse, as well as an increase in baseline activity between pulses. This pattern contrasts markedly with many other stretch-activated channels whose activation is limited to the duration of the suction pulse. 3. Application of fatty acids augmented the response to stretch. In contrast, application of 10 microM defatted albumin, which removes fatty acids from membranes, rapidly and reversibly decreased the response to stretch. 4. These results are consistent with the hypothesis that fatty acids which are generated by mechanical stimuli, perhaps by mechanically activated phospholipases, are the intermediaries in activation of certain mechanically sensitive ion channels.

Albumins↗
PubMed1995

Cost and utilisation of community services for people with HIV infection in London.

This study aimed to describe the use and costs of community services for HIV-infected people by disease stage, sex and transmission category (homosexual, heterosexual, injecting drug use) by use of a prospective cohort study in which people were followed up for six months. There were two major components; gathering quantitative information on service utilisation from people with HIV infection using two interviewer-administered questionnaires and six self-completed monthly diaries; and estimating the costs of the services provided. People were recruited from two London clinics: the Jefferiss Wing Genito-urinary Medicine (GUM) clinic at St. Mary's Hospital, Paddington, and the Patrick Clements GUM clinic at the Central Middlesex Hospital, Harlesden. Costing data was obtained from providers of community services throughout Greater London. The main outcome measures were contacts per person-year, and costs per person-year, for all community services stratified by service sector. The people studied each made, on average, 139 community service contacts per year at a cost of 2,806 pounds; there was little difference in average utilisation between the three transmission categories. There were differences in both the utilisation of services and costs within the formal and informal sectors for subjects from different disease stages. Although the average number of contacts per person-year were similar for women and men, the total cost of community services was higher for women than for men, reflecting the differences in types of services used. The results indicated a high proportion of total care costs for people with HIV and AIDS is incurred through community-based social care.(ABSTRACT TRUNCATED AT 250 WORDS)

Community Health Services↗
PubMed1994

Structural requirements for charged lipid molecules to directly increase or suppress K+ channel activity in smooth muscle cells. Effects of fatty acids, lysophosphatidate, acyl coenzyme A and sphingosine.

We determined the structural features necessary for fatty acids to exert their action on K+ channels of gastric smooth muscle cells. Examination of the effects of a variety of synthetic and naturally occurring lipid compounds on K+ channel activity in cell-attached and excised membrane patches revealed that negatively charged analogs of medium to long chain fatty acids (but not short chain analogs) as well as certain other negatively charged lipids activate the channels. In contrast, positively charged, medium to long chain analogs suppress activity, and neutral analogs are without effect. The key requirements for effective compounds seem to be a sufficiently hydrophobic domain and the presence of a charged group. Furthermore, those negatively charged compounds unable to "flip" across the bilayer are effective only when applied at the cytosolic surface of the membrane, suggesting that the site of fatty acid action is also located there. Finally, because some of the effective compounds, for example, the fatty acids themselves, lysophosphatidate, acyl Coenzyme A, and sphingosine, are naturally occurring substances and can be liberated by agonist-activated or metabolic enzymes, they may act as second messengers targeting ion channels.

Acyl Coenzyme A↗