Measurement of systemic oxygen uptake during low-flow anaesthesia with a standard technique vs. a novel method

We assessed agreement between measurement of systemic oxygen uptake using the Fick-derived method, and a novel method described by Biro, based on the difference in oxygen concentrations of the delivered fresh gas and the gas circulating in the circle system. Twenty-nine patients undergoing elective cardiac surgery were studied during stable haemodynamic and ventilatory conditions. Systemic oxygen uptake was measured using the two methods in each patient before and after cardiopulmonary bypass. Limits of agreement were found to be wide (-162 to 311 ml.min-1 before bypass, and -257 to 401 ml.min-1 after bypass), indicating poor agreement between the methods. No significant difference was found between the pre- and post cardiopulmonary bypass values for each method. We conclude that the Biro method, although attractive in terms of its simplicity, is an unreliable measure of systemic oxygen uptake under these conditions.

The influence of 4G/5G polymorphism in the plasminogen activator inhibitor-1 gene promoter on the incidence, growth and operative risk of abdominal aortic aneurysm

BACKGROUND

a single base pair deletion/insertion (4G/5G) polymorphism in the plasminogen activator inhibitor (PAI-1) promoter appears to influence PAI-1 synthesis (increased PAI-1 and inhibition of fibrinolysis with the 4G allele) and survival after severe trauma.

OBJECTIVE

to identify whether the 4G/5G polymorphism influences the natural history of abdominal aortic aneurysm (AAA).

METHODS

Four hundred and sixty patients with small AAA were genotyped for the 4G/5G polymorphism. AAA growth was assessed from serial ultrasonographic measurements, subject to linear regression analysis. Mortality following eventual elective surgery was recorded.

RESULTS

the frequency of the 3 genotypes (4G4G, 4G5G and 5G5G) was in Hardy-Weinberg equilibrium and similar to that in a healthy population. The mean aneurysm growth rate was 0.37, 0.35 and 0.44 cm/year respectively for patients of 4G4G, 4G5G and 5G5G genotype respectively, p = 0.07. The 30d mortality following open elective aneurysm repair was 8% (7/87), 8% (11/145) and 0% (0/56) for patients of 4G4G, 4G5G and 5G5G genotype respectively, giving a higher mortality for those carrying a 4G allele p = 0.03.

CONCLUSIONS

polymorphism of the PAI-1 gene promoter does not influence the development of AAA, although AAA growth is faster for patients of 5G5G genotype. However, this genotype (5G5G), which is associated with enhanced fibrinolysis, appears protective following open aneurysm repair. This effect of PAI-1 genotype on survival following surgery is likely to have widespread significance in vascular and general surgery.

MRI measures of entorhinal cortex vs hippocampus in preclinical AD

BACKGROUND

MRI measures of the entorhinal cortex and the hippocampus have been used to predict which nondemented individuals with memory problems will progress to meet criteria for AD on follow-up, but their relative accuracy remains controversial.

OBJECTIVES

To compare MRI measures of the entorhinal cortex and the hippocampus for predicting who will develop AD.

METHODS

MRI volumes of the entorhinal cortex and the hippocampus were obtained in 137 individuals comprising four groups: 1) individuals with normal cognition both at baseline and after 3 years of follow-up (n = 28), 2) subjects with memory difficulty but not dementia both at baseline and after 3 years of follow-up (n = 73), 3) subjects with memory difficulty at baseline who were diagnosed with probable AD within 3 years of follow-up (n = 21), and 4) patients with mild AD at baseline (n = 16).

RESULTS

Measures of both the entorhinal cortex and the hippocampus were different for each of the pairwise comparisons between the groups (p < 0.001) and were correlated with tests of memory (p < 0.01). However, the volume of the entorhinal cortex differentiated the subjects from those destined to develop dementia with considerable accuracy (84%), whereas the measure of the hippocampus did not.

CONCLUSION

These findings are consistent with neuropathologic data showing substantial involvement of the entorhinal cortex in the preclinical phase of AD and suggest that, as the disease spreads, atrophic change develops within the hippocampus, which is measurable on MRI.

Outreach health adviser in a community clinic screening programme improves management of genital chlamydia infection

OBJECTIVE

To assess the effectiveness of an outreach health adviser on treatment, partner notification and outcome for clients diagnosed with genital chlamydia (CT) infection at a community young people's clinic.

METHODS

From August 1999 to March 2000, a genitourinary medicine (GUM) based health adviser helped to develop testing and undertook outreach management of clients aged under 26 years diagnosed with CT infection. In addition to facilitating referral to GUM, she gave antibiotic treatment based on a GUM derived patient group direction to those not wishing to travel to the GUM clinic. She also advised them on contact tracing and the need for a compliance check (CC).

RESULTS

Chlamydia positive tests with ligase chain reaction (LCR), on first void urine, were obtained for 62 (12.9%) of 481 female clients, one (5%) of 20 male clients, and nine (53%) of 17 male contacts of female positive cases. All 72 testing positive received their result and were treated. Two urine samples positive for CT showed positive LCR tests for gonorrhoea. Proportions of named contacts seen (67%) and reattendances for compliance checks (60%) were similar to those for women seen in GUM services.

CONCLUSIONS

Health adviser input with the ability to treat can be effective in reducing the growth of identified but untreated genital chlamydia infection consequent upon community based screening. Such a strategy appears comparable with, and can add to, GUM based treatment of infection. It helps to address the need for alternative management strategies in the light of the national sexual health strategy.

Development of a urinary biomarker for exposure to the organophosphate propetamphos: data from an oral and dermal human volunteer study

Propetamphos is a member of the vinyl phosphate group of insecticides and is mainly used for sheep dipping. There have been no published metabolic studies on the effect of propetamphos in man to date, although the present authors have published the identification of a metabolite. The present paper presents data from a human volunteer study investigating the toxicokinetics of the organophosphorus pesticide propetamphos following oral and dermal exposure. Five volunteers ingested a propetamphos dose of 10 micrograms kg-1 (35 nmol kg-1) body weight. Following a washout of 4 weeks, a 100 mg (356 mumol) dermal dose of propetamphos was applied, occluded to 80 cm2 of the inner forearm, for 8 h to the same five volunteers. In a pilot study (several weeks before the main study), one volunteer also received an occluded dermal dose of 50 mg (178 mumol) propetamphos. Unabsorbed propetamphos on the skin was washed off after 8 h and collected. Blood and urine samples were collected over 30 and 54 h for the oral and dermal exposures respectively. Blood samples were analysed for plasma and erythrocyte cholinesterase. Urine samples were analysed for a urinary metabolite of propetamphos: methylethylphosphoramidothioate (MEPT). Following oral and dermal exposure, peak urinary MEPT levels occurred at 1 and 10-12 h respectively. The apparent urinary elimination half-lives of MEPT had means of 1.7 h (oral exposure) and 3.8 h (dermal exposure). Approximately 40% of the oral dose and 1% of the dermal dose were recovered as urinary MEPT or metabolites, which could be hydrolysed to MEPT. Approximately 90% of the dermal dose was recovered from the skin washings. Data from a volunteer showed that a doubling of the dermal dose resulted in approximately double the concentration of total MEPT. Alkaline hydrolysis of urine samples increased the level of MEPT detected after both oral and dermal doses. The increase was greater and statistically significant (p < 0.001, paired t-test) for the dermal dose. This increase in MEPT suggests the presence of other MEPT-containing metabolites or conjugates. The difference in the increase between oral and dermal doses raises the question of a difference in metabolism between the two routes. No individual showed a significant depression compared with their pre-exposure levels of erythrocyte acetyl cholinesterase or plasma cholinesterase activity for either dosing route. However, on a group basis, there was a statistically significant mean depression in plasma cholinesterase activity at 8 and 24 h for oral exposure, with a maximum mean depression of 7% from pre-exposure levels at 8 h. Hydrolysis of urine samples had the effect of reducing the interindividual coefficient of variation (CV) for total excretion of MEPT following both oral (CV reduced from 36 to 8%) and dermal (CV reduced from 40 to 17%) exposure. The ability to detect and follow the elimination of low doses of propetamphos by measurement of 'total' (after hydrolysis) urinary MEPT suggests it is a suitable biomarker of propetamphos exposure. The comparatively short elimination half-lives suggest a strategy for biological monitoring of occupational exposure based on samples collected at the end of the shift.

Development and validation of a competitive immunoassay for urinary S-phenylmercapturic acid and its application in benzene biological monitoring

An immunoassay that quantifies urinary S-phenylmercapturic acid (PMA), a benzenespecific biomarker, has been developed and its potential usefulness as a screening tool for monitoring occupational exposure to benzene has been demonstrated. Analytical reliability has been confirmed by correlation of results with gas chromatography-mass spectrometry (GC/MS) data (R = 0.92). The assay has been configured as a competitive enzyme-linked immunosorbent assay (ELISA) to facilitate rapid throughput of samples. The ELISA has a working range of 40-1200 nmoll-1 urinary PMA and appears to be unaffected by the presence of structurally related urinary metabolites. Background levels of 0-1.9 mumol PMA/mol creatinine (mean 0.9 mumol mol-1, n = 32) were measured in nonsmoking control subjects. Recent exposures to benzene (8 h time-weighted averages-TWA), during diverse industrial processes, over the range 0-4.8 ppm were identified by application of the assay in biological monitoring programmes.

Using a revised asthma morbidity index to identify varying patterns of morbidity in U.K. general practices

Both in terms of morbidity and mortality, the therapeutic and organizational management of asthma pose a considerable and continuing challenge to healthcare delivery. One element in attempts to meet this challenge is the recognition of appropriate outcome measures to assess progress in tackling the burden of this disease. This study therefore aimed to assess pragmatically the effectiveness of a revised asthma morbidity index in identifying varying patterns of morbidity in U.K. general practices. A postal survey was conducted of 2,762 patients believed to have or have had asthma from the lists of 12 general practices within the Eden Valley in Cumbria, using a questionnaire which combined the revised Jones morbidity index with questions on age, medication and perception of current asthma. Prescribing data were also recovered for 11 of the practices for the quarter within which the postal survey was conducted. Responses were obtained from 2,123 subjects (77%), of whom 1,474 (70%) believed themselves to be currently asthmatic. In this group, 18% reported low morbidity 34% medium morbidity and 48% high morbidity Age and inhaled steroid use were both positively and significantly associated with high morbidity. Those taking inhaled steroids were 1.4 times more likely to report high morbidity than those nottaking steroids. The prescribed corticosteroid/bronchodilator ratio for cost was both negatively and significantly associated with high morbidity. The revised morbidity index is a simple tool of use in the surveillance of asthma in primary care. It identifies spectra of morbidity which vary between practices, which may be of use in assessing the quality of asthma care provided in the community.

Children and road safety: increasing knowledge does not improve behaviour

BACKGROUND

Programmes designed to teach children about road safety have often failed to assess their effectiveness in terms of either an increase in children's knowledge or an improvement in children's behaviour.

AIM

The two studies reported here sought to address both issues, by focusing on the abilities of Primary 1 children (5 years old).

SAMPLE

A total of 120 Primary 1 children within the age range 4-5 years old participated in this study, drawn from three different primary schools within an educational district of Scotland.

METHODS

In the first study the effects of three different road safety interventions were tested, all of which employed commercially marketed products: 1) a three-dimensional model of the traffic environment; 2) a road safety board game; and 3) illustrated posters and flip-chart materials. In the second study the transfer of knowledge to children's behaviour in a real-life traffic environment was tested, using a subsample of 47 children who had taken part in the first study.

RESULTS

Results from the first study showed, surprisingly, that all three interventions were effective in increasing children's knowledge about safe and dangerous locations at which to cross the street, and that this knowledge was retained for a period of six months. Study 2, however, showed that increased knowledge did not result in improved traffic behaviour. Children who had received training performed no better than children in a control group.

CONCLUSION

These findings highlight the need to distinguish between children's road safety knowledge and their behaviour, particularly for teachers and parents, who may mistakenly believe that children who know more will be safer on the road.

Identification of a possible biomarker for colophony exposure

Colophony is known to cause occupational asthma and dermatitis. Biological monitoring may be useful in assessing exposure. This paper describes a method for the analysis of dehydroabietic acid in urine and its potential use as a marker of colophony exposure. The method involves hydrolysis, solvent extraction, derivatization and analysis by gas chromatography-mass spectrometry. Twenty-eight workers from a soldering factory in South Africa were monitored. Results showed that levels of dehydroabietic acid in urine may be correlated with a subjective assessment of exposure.

Frontal lobe function, sleep loss and fragmented sleep

Recent experimental studies involving total sleep loss, sleep reduction and clinically related sleep fragmentation report impaired performance on tasks of frontal lobe or executive function, including measures of verbal fluency, creativity and planning skills. Severity of sleep disturbance in obstructive sleep apnoea syndrome (OSAS) is correlated with level of executive impairment, with some residual impairment despite treatment (continuous positive airway pressure - CPAP). Executive impairment appears to be more closely related to hypoxaemic events rather than daytime sleepiness. Studies of electroencephalographic (EEG) changes throughout the course of sleep and following sleep deprivation as well as functional neuroimaging and psychophysiological changes (event-related potentials - ERPs) following sleep deprivation provide further indication of the relative importance of the frontal regions of the brain to sleep. However, neurocognitive studies present many inconsistencies, task classification is often ambiguous and, in the absence of any unifying explanation at the level of cognitive mechanisms, the overall picture is one of a disparate range of impairment following sleep loss and sleep fragmentation. Poorly defined concepts of frontal lobe function, executive function, memory and attention, using tasks largely developed with more severe deficit levels in mind, create further difficulties in interpreting current findings.

Characterization of surface antigen from Lyme disease spirochete Borrelia burgdorferi

Borrelia burgdorferi, the Lyme disease spirochete, possesses a surface protein, VlsE (variable major protein-like sequence, expressed), that undergoes antigenic variation. Unlike conserved regions of other proteins involved in antigenic variation, the most conserved invariable region of VlsE is immunodominant in Lyme-disease patients. Physicochemical analyses of pure recombinant VlsE yielded the following results: The protein appeared oligomeric in solution, with a secondary structure dominated by alpha-helices. Thermal denaturation (pH 7) probed by calorimetry involved two transitions: oligomer-to-monomer conversion (around 40 degrees C) followed by protein unfolding (55 +/- 1 degrees C). Chemical denaturation monitored by far-UV circular dichroism (20 degrees C, pH 7) sensed only polypeptide unfolding and took place in a single transition (Delta G(U)(H(2)O) = 23 +/- 2 kJ/mol). VlsE did not adopt a native structure at pH 3; at pH 10 the stability was significantly reduced. Knowledge of biophysical properties of VlsE may aid in understanding the mechanism of VlsE antigenic variation in B. burgdorferi.

Correlates of clinic referral for early conduct problems: variable- and person-oriented approaches

The current study utilized both variable- and person-oriented analyses to examine correlates of early disruptive behavior problems. Participants included 80 preschool boys referred to a child psychiatry clinic and diagnosed with oppositional defiant disorder (with or without attention-deficit hyperactivity disorder) and 80 case-matched normal comparison boys. The study examined four domains of correlates: vulnerable child characteristics, poor parenting practices, insecure attachment, and adverse family ecology. Results indicated that the combination of these factors provided relatively high sensitivity (81%) and specificity (85%), clearly differentiating referred from comparison boys. A dramatic increase in clinic status occurred when three or more factors were present, and specific combinations of factors were differentially predictive of conduct problems. However, no correlates were found to be either necessary or sufficient for clinic status. By maintaining the integrity of individual cases, person-oriented analyses were able to answer different questions than more traditional variable-oriented analyses. Discussion focuses on the value of person-oriented analyses for understanding heterogeneous clinical groups.

The implementation of venous leg ulcer guidelines: process analysis of the intervention used in a multi-centre, pragmatic, randomized, controlled trial

The production and implementation of clinical practice guidelines is currently a high political priority and a rapidly developing field within healthcare in the United Kingdom (UK). Their purpose is to provide clinicians with a synthesis of the best available external evidence and operationalize the implementation of evidence-based practice. Despite indications that clinical guidelines can make a difference to the quality of patient care, there is some evidence that practitioners struggle with their application. The aim of this paper is to report one element of a trial undertaken by three collaborating universities in the Northern and Yorkshire Region of the UK health service during 1997-1998. The objective was to understand what makes guidelines acceptable and usable, or otherwise, to health professionals. The findings reported in this paper describe the process of care in those general practices that elected to implement guidelines for the management of patients with venous leg ulcers. We conclude that planning for training, resource and quality improvement processes must be built into a team's guidelines implementation procedures. A preliminary needs analysis of the contextual 'hurdles and levers' within each primary healthcare team is also necessary to identify individual issues that must be addressed if the process is to succeed. These findings provide some lessons for successful implementation of clinical guidelines in general. Recommendations for nursing policy makers, managers, practitioners and researchers are included.

Effectiveness of optometrist screening for diabetic retinopathy using slit-lamp biomicroscopy

PURPOSE

To assess the effectiveness of optometrists as screeners for diabetic retinopathy using slit-lamp binocular indirect ophthalmoscopy through dilated pupils.

METHODS

Prospective study of a screening scheme. Screening was performed by 27 locally accredited optometrists in their practice. The referral protocol used a new simple grading system of retinopathy, especially designed for use in an optometrist screening programme. All positive referrals and 10% of negative referrals were reexamined by an ophthalmologist. Sensitivity, specificity, likelihood ratios and technical failure rates were calculated.

RESULTS

The optometrists screened 4904 people with diabetes in 18 months. 'Subthreshold' (screen negative) reports accounted for 4438 (90.5% of 4904); 429 (9.67%) of these were re-examined at secondary screening. There was disagreement regarding grading in 13 patients, of whom 5 (1.16% of 429) had sight-threatening retinopathy (STDR); this extrapolates to 52 patients if all the 4438 test-negatives had been examined. Of the 371 'threshold' patients, 112 (30.18%) were false positives; the commonest cause for false positive referral was drusen in patients with background diabetic retinopathy. The sensitivity for identification of STDR was 76% (95% CI 70% to 81%) and specificity 95% (95% CI 95% to 96%). The likelihood ratio of a positive test indicating STDR was 16.54 (95% CI 14.17 to 19.23) and that of a negative test 0.25 (95% CI 0.20 to 0.32). The technical failure rate was 0.2%.

CONCLUSIONS

Suitably trained and accredited community optometrists performed well when screening for diabetic retinopathy using slit-lamp biomicroscopy through a dilated pupil. This was facilitated by the use of simple grading and referral criteria. The sensitivity, positive likelihood ratio and specificity were high.

Prevalence of blindness and visual impairment in a population of people with diabetes

PURPOSE

To assess the prevalence of visual impairment and the underlying causes in a population of people with diabetes.

METHOD

A population-based study of a defined population of people with diabetes in a district in the North West of England was done. There were 7652 known people with diabetes, representing 2.12% of target general population of 361050. The main outcome measures were the prevalence of blindness and significant visual impairment (less than 6/18 corrected vision in their better eye) and the underlying causes.

RESULTS

Visual acuity data on 6482 (84.7%) of the 7652 individuals were obtained. Of these, 184 had significant visual impairment (prevalence 2.84%) including 49 who were blind (vision of less than 3/60 in their better eye, prevalence 0.75%); if blindness was defined as vision less than or equal to 6/60, prevalence was 1.13% (n = 73). Details of 3 individuals could not be ascertained. Only 67 were registered, either as partially sighted (n = 42) or as blind (n = 25). In the majority (n = 133; 68%) of these 181 individuals the visual impairment was due to causes other than diabetic retinopathy.

CONCLUSIONS

The prevalence of blindness and visual impairment in our population of people with diabetes was low. Non-diabetic eye disease accounted for the majority of this visual impairment. This provides essential baseline data against which future progress can be assessed. Screening and treatment can greatly reduce the incidence of visual impairment due to diabetic retinopathy, but its impact on overall visual impairment rates in the population of people with diabetes will be more modest.

An economic evaluation of community water fluoridation

OBJECTIVE

The purpose of this research was to assess the local cost savings resulting from community water fluoridation, given current exposure levels to other fluoride sources.

METHODS

Adopting a societal perspective and using a discount rate of 4 percent, we compared the annual per person cost of fluoridation with the cost of averted disease and productivity losses. The latter was the product of annual dental caries increment in nonfluoridated communities, fluoridation effectiveness, and the discounted lifetime cost of treating a carious tooth surface. We obtained or imputed all parameters from published studies and national surveys. We conducted one-way and three-way sensitivity analyses.

RESULTS

With base-case assumptions, the annual per person cost savings resulting from fluoridation ranged from $15.95 in very small communities to $18.62 in large communities. Fluoridation was still cost saving for communities of any size if we allowed increment, effectiveness, or the discount rate to take on their worst-case values, individually. For simultaneous variation of variables, fluoridation was cost saving for all but very small communities. There, fluoridation was cost saving if the reduction in carious surfaces attributable to one year of fluoridation was at least 0.046.

CONCLUSION

On the basis of the most current data available on the effectiveness and cost of fluoridation, caries increment, and the cost and longevity of dental restorations, we find that water fluoridation offers significant cost savings.

Efficacy, safety, and use of ginkgo biloba in clinical and preclinical applications

Ginkgo biloba is a dioecious tree with a history of use in traditional Chinese medicine. Although the seeds are most commonly employed in traditional Chinese medicine, in recent years standardized extracts of the leaves have been widely sold as a phytomedicine in Europe and as a dietary supplement in the United States. The primary active constituents of the leaves include flavonoid glycosides and unique diterpenes known as ginkgolides; the latter are potent inhibitors of platelet activating factor. Clinical studies have shown that ginkgo extracts exhibit therapeutic activity in a variety of disorders including Alzheimer's disease, failing memory, age-related dementias, poor cerebral and ocular blood flow, congestive symptoms of premenstrual syndrome, and the prevention of altitude sickness. Due in part to its potent antioxidant properties and ability to enhance peripheral and cerebral circulation, ginkgo's primary application lies in the treatment of cerebrovascular dysfunctions and peripheral vascular disorders.

The effects of varying resistance-training loads on intermediate- and high-velocity-specific adaptations

The purpose of this study was to compare changes in velocity-specific adaptations in moderately resistance-trained athletes who trained with either low or high resistances. The study used tests of sport-specific skills across an intermediate- to high-velocity spectrum. Thirty NCAA Division I baseball players were randomly assigned to either a low-resistance (40-60% 1 repetition maximum [1RM]) training group or a high-resistance (70-90% 1RM) training group. Both of the training groups intended to maximallv accelerate each repetition during the concentric phase (IMCA). The 10 weeks of training consisted of 4 training sessions a week using basic core exercises. Peak force, velocity, and power were evaluated during set angle and depth jumps as well as weighted jumps using 30 and 50% 1RM. Squat 1RMs were also tested. Although no interactions for any of the jump tests were found, trends supported the hypothesis of velocity-specific training. Percentage gains suggest that the combined use of heavier training loads (70-90% 1RM) and IMCA tend to increase peak force in the lower-body leg and hip extensors. Trends also show that the combined use of lighter training loads (40-60% 1RM) and IMCA tend to increase peak power and peak velocity in the lower-body leg and hip extensors. The high-resistance group improved squats more than the low-resistance group (p < 0.05; +22.7 vs. + 16.1 kg). The results of this study support the use of a combination of heavier training loads and IMCA to increase 1RM strength in the lower bodies of resistance-trained athletes.

Transgenic mice with cardiac-specific expression of activating transcription factor 3, a stress-inducible gene, have conduction abnormalities and contractile dysfunction

Activating transcription factor 3 (ATF3) is a member of the CREB/ATF family of transcription factors. Previously, we demonstrated that the expression of the ATF3 gene is induced by many stress signals. In this report, we demonstrate that expression of ATF3 is induced by cardiac ischemia coupled with reperfusion (ischemia-reperfusion) in both cultured cells and an animal model. Transgenic mice expressing ATF3 under the control of the alpha-myosin heavy chain promoter have atrial enlargement, and atrial and ventricular hypertrophy. Microscopic examination showed myocyte degeneration and fibrosis. Functionally, the transgenic heart has reduced contractility and aberrant conduction. Interestingly, expression of sorcin, a gene whose product inhibits the release of calcium from sarcoplasmic reticulum, is increased in these transgenic hearts. Taken together, our results indicate that expression of ATF3, a stress-inducible gene, in the heart leads to altered gene expression and impaired cardiac function.