A controlled study of the effects of isosorbide mononitrate on arterial blood pressure and pulse wave form in systolic hypertension

OBJECTIVE

To determine the effect of an extended-release nitrate preparation on the arterial pulse wave and blood pressure of patients in whom systolic blood pressure was elevated in part by exaggerated pulse-wave reflectance.

DESIGN

A double-blind randomized placebo-controlled crossover study was carried out.

PATIENTS AND METHODS

The subjects were ten elderly patients with systolic hypertension resistant to conventional anti-hypertensive therapy. Pharmacodynamic responses to 2-week courses of placebo/isosorbide mononitrate (ISMN) were assessed in seven subjects by an ambulatory blood pressure monitor, and in all ten subjects by standard sphygmomanometry, arterial pulse-wave analysis and measurement of plasma nitrate concentration during peak and trough.

RESULTS

Ambulatory systolic blood pressure was decreased by ISMN (P < 0.02) between 1000 and 2200 h. Ambulatory diastolic blood pressure fell with ISMN (P < 0.01) during the last 4 h of this period. At peak plasma nitrate levels, ISMN decreased the aortic systolic blood pressure (P < 0.01), ejection peak (P < 0.02) and augmentation component (P < 0.001) of the pulse wave; heart rate increased slightly (P < 0.03).

CONCLUSION

ISMN has a role as an adjunct in the anti-hypertensive therapy of patients with refractory systolic hypertension due to exaggerated pulse-wave reflectance.

Prediction of perinatal outcome in fetuses suspected to have intrauterine growth restriction: Doppler US study of fetal cerebral, renal, and umbilical arteries

PURPOSE

To determine and compare the diagnostic performance of fetal middle cerebral (MCA), renal (RA), and umbilical (UA) arterial Doppler ultrasonography (US) for prediction of adverse perinatal outcome in suspected intrauterine growth restriction (IUGR).

MATERIALS AND METHODS

Two hundred ninety-three small-for-gestational age fetuses (24-39 weeks at recruitment and US-estimated weight or abdominal circumference below 10th percentile) were prospectively examined with Doppler US of the UA, MCA, and RA. Clinicians were blinded to MCA and RA Doppler measurements.

RESULTS

Seventy-six fetuses (25.9%) had at least one major or minor adverse perinatal outcome. Major outcomes included stillbirth, neonatal death, neurologic complication, and necrotizing enterocolitis. The MCA pulsatility index (PI), compared with the UA PI and RA PI, was more sensitive (72.4% vs 44.7% and 8.3%) but less specific (58.1% vs 86.6% and 92.6%) in predicting adverse outcome. The UA PI had the highest positive likelihood ratio (ratio, 3.3); the MCA PI had the lowest negative likelihood ratio (ratio, 0.48). When gestational age at the first Doppler US examination was less than 32 weeks, the MCA PI had a sensitivity of 95.5% and negative predictive value of 97.7% for major adverse outcome (negative likelihood ratio, 0.10).

CONCLUSION

In suspected IUGR, while an abnormal UA PI is a better predictor of adverse perinatal outcome than an abnormal MCA or RA PI, a normal MCA PI may help to identify fetuses without major adverse perinatal outcome, especially before 32 weeks gestational age.

Bacterial phosphatidylinositol-specific phospholipase C: structure, function, and interaction with lipids

The bacterial phosphatidylinositol-specific phospholipase C (PI-PLC) is a small, water-soluble enzyme that cleaves the natural membrane lipids PI, lyso-PI, and glycosyl-PI. The crystal structure, NMR and enzymatic mechanism of bacterial PI-PLCs are reviewed. These enzymes consist of a single domain folded as a (betaalpha)(8)-barrel (TIM barrel), are calcium-independent, and interact weakly with membranes. Sequence similarity among PI-PLCs from different bacterial species is extensive, and includes the residues involved in catalysis. Bacterial PI-PLCs are structurally similar to the catalytic domain of mammalian PI-PLCs. Comparative studies of both prokaryotic and eukaryotic isozymes have proved useful for the identification of distinct regions of the proteins that are structurally and functionally important.

Preventing stroke in patients with transient ischemic attacks

Stroke is the third most common overall cause of death and the leading cause of adult disability in the United States. New therapeutic interventions instituted in the period immediately after a stroke have revolutionized the approach to ischemic cerebrovascular disease. Recognition of a transient ischemic attack provides an opportunity to prevent a subsequent stroke. Specific stroke prevention treatment depends on the cause of the transient ischemic attack, its cerebrovascular localization and the presence of associated coexisting medical problems. Modification of stroke risk factors is the principal therapeutic approach. Antiplatelet agents and anticoagulants have been shown to be effective in reducing the occurrence of stroke in certain populations. Several well-designed studies have recently demonstrated the effectiveness of carotid endarterectomy in preventing strokes related to extracranial carotid artery disease.

Pharmacoeconomics of lipid lowering therapy in Ireland

Increases in expenditure on medicines above the level of increases in health care are generally, a feature of all Western health systems. From the early 1990's, the average annual growth rate (AAGR) in pharmaceutical expenditure exceeded the AAGR in health among all the European member states 1. In Ireland, the expenditure on drugs, as a percentage of health care spending, was 7.1% in 1987 compared with 9.2% in 1997. The state expenditure on medicines increased from 165.8 million Pounds in 1993 to 278 million Pounds in 1998 representing an average increase of 11% each year. All the available evidence indicates that the expenditure on medicines will continue to show real growth, and take an increasing share of the total health care budget. Analysis shows that the main reasons driving such growth include those of "product mix"--the prescribing of newer, more expensive medicines, in addition to the 'volume effect' comprising growth in the number of tablets per prescription. These two factors account for 80% of the observed increase in drug cost 2. Six therapeutic classes accounted for 16 of the top 20 most expensive drugs prescribed under the GMS in 1998 3. These areas can be classified as follows: peptic ulcer disease, asthma, hypertension/cardiac failure, antidepressants, anti inflammatory and lipid lowering drugs. In this article we discuss the clinical evidence base, and the pharmacoeconomic implications of lipid lowering therapy in this country.

Interaction of sildenafil and indinavir when co-administered to HIV-positive patients

OBJECTIVES

The prevalence of erectile dysfunction in HIV-infected men is estimated to be 33%. Sildenafil citrate (Viagra; Pfizer Ltd, Sandwich, Kent, UK) is the first oral drug for this condition. Since sildenafil and the protease inhibitors are both metabolized by, and act as inhibitors of cytochrome P450 3A4, we evaluated the pharmacokinetics of the combination sildenafil plus indinavir in HIV-infected patients.

DESIGN AND METHODS

Six patients at steady state in treatment with indinavir participated in the study. On the first day blood samples for indinavir assay were drawn at times 0, 1, 2, 3, 4, 6 and 8 h after dosing. On the second study day patients received a single dose of 25 mg of sildenafil in addition to their routine morning medication. Blood samples were taken as described. Separated plasma was stored at -80 degrees C until analysis by high performance liquid chromatography. In a parallel study, the effect of indinavir, ritonavir, saquinavir and nelfinavir on the in vitro hepatic metabolism of sildenafil was assessed.

RESULTS

The geometric mean area under the concentration curve for 0-8 h (AUC0-8h) and maximum plasma concentration (Cmax) for indinavir were 19.69 microg/ml h (range, 9.19-31.99 microg/ml h) and 7.02 microg/ml (range, 2.33-16.17 microg/ml), respectively, on the first study day. In the presence of sildenafil, the mean AUC0-8h and Cmax of indinavir were 22.37 microg/ml h [range, 10.08-37.25 microg/ml h; 95% confidence interval (CI) for difference between means, -15 to 13.25) and 9.11 microg/ml (range, 3.41-22.78 microg/ml; 95% CI, -13 to 6.37), respectively. The geometric mean AUC0-8h and Cmax for sildenafil were 1631 ng/ml h (range, 643-2970 ng/ml h) and 384 ng/ml (range, 209-766 ng/ml) respectively. The AUC for sildenafil was 4.4 times higher than data from historical controls given either 50 mg or 100 mg of sildenafil and dose normalized to 25 mg. Indinavir was a potent inhibitor of sildenafil hepatic metabolism in vitro [concentration producing 50% inhibition of control enzyme activity (IC50) = 0.39 +/- 0.17 microM, mean +/- SD].

CONCLUSIONS

Co-administration of sildenafil 25 mg did not significantly alter the plasma indinavir levels. However, plasma sildenafil AUC was markedly increased in the presence of indinavir compared with historical controls. From the in vitro data, the mechanism of increase is indinavir inhibition of the hepatic metabolism of sildenafil. The magnitude of this interaction suggests a lower starting dose of sildenafil may be more appropriate in this clinical setting.

The confirmation and control of metabolic caffeine in standardbred horses after administration of theophylline

The origin of caffeine detections in equine serum and urine after theophylline administrations was examined. Three different preparations containing theophylline were administered to standardbred mares. Both blood and urine samples were collected. Caffeine was detected and quantified in theophylline administration samples by high performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). Further in vitro analysis showed that caffeine metabolites were not detected when caffeine, or caffeine-containing products, were added to urine. Data derived from HPLC-UV and LC-MS-MS analysis of dosages of theophylline and caffeine are used to propose the establishment of a threshold limit to control and discern between metabolic and administered caffeine concentrations. A serum caffeine concentration of 250 ng/mL and a urine caffeine concentration of 1000 ng/mL are suggested. Based on the data supplied, these threshold concentrations could effectively control orally administered caffeine in racehorses, up to the dosage used in this work, up to 72 h before sampling time.

Stress response decreases the interleukin-1beta-induced production of complement component C3 in human intestinal epithelial cells

Interleukin-1beta (IL-1beta) increases the production of complement component C3 in enterocytes. Heat shock regulates the response to cytokines and other inflammatory mediators in various cell types. We tested the hypothesis that the heat-shock response regulates IL-1beta-induced C3 production in the enterocyte. Cultured Caco-2 cells, a human intestinal epithelial cell line, were treated with sodium arsenite (10-500 microM) for 1 h or subjected to hyperthermia (43 degrees C) for 1-4 h, and allowed to recover for 1 h. The cells were then treated with IL-1beta (0.5 ng/ml) for up to 24 h, whereafter C3 levels were measured by ELISA and C3 mRNA by Northern blot analysis. Heat-shock protein of 72 kDa (hsp72) was determined by Western blot analysis. Treatment of the cells with sodium arsenite or subjecting them to hyperthermia induced the expression of hsp72. The IL-1beta-induced expression of C3 mRNA and C3 production were down-regulated by hyperthermia and sodium arsenite in a dose-dependent fashion. The results suggest that the stress response induced by hyperthermia or sodium arsenite decreases IL-1beta-induced C3 production in human enterocytes.

Evaluation of Traditional Classroom Teaching Methods Versus Course Delivery Via the World Wide Web

Higher education is moving with deliberate speed to an electronic classroom. Much has been published on faculty experiences with World Wide Web (WWW) course delivery. However, little research exists on the evaluation of these methods. The purpose of this study was to evaluate students' perceptions of two approaches to teaching: classroom and WWW modules. Classroom methods were rated significantly higher in relation to content, interaction, participation, faculty preparation, and communication. Technical skills were rated higher for WWW modules. Critical thinking and time allotted for assignments were not significantly different between classroom and WWW instruction. Open-ended comments were rich and supported both positive and negative aspects of classroom and WWW-based modules. Implications call for creativity in course development, course redesign and orientation, active communication with students, support for technical problems, faculty development, and university-wide planning through partnerships.

The European Donor Hospital Education Programme (EDHEP): addressing the training needs of doctors and nurses who break bad news, care for the bereaved, and request donation

The competence of critical care staff when it comes to death and organ donation can make the difference between a family's agreeing to or refusing the latter. Doctors and nurses often feel uncomfortable approaching relatives about donation and attribute this to a lack of training. Bereaved relatives express dissatisfaction with inappropriate communication and support when brain death is announced and thereafter when a request for donation is made. The European Donor Hospital Education Programme (EDHEP) was designed to meet the training needs of critical care staff in breaking bad news, caring for the bereaved, and requesting donation. EDHEP is a two-part educational package consisting of a presentation about the donor shortage followed by a one-day workshop. The implementation of EDHEP throughout the world has been facilitated through effective national working groups and standardised "train the trainer" courses. Several countries anecdotally report increases in donation following implementation. Controlled evaluation of the effect(s) of EDHEP, which started at the end of 1995, focuses on the satisfaction of the participants with EDHEP, on the competence of the participants in breaking bad news and requesting donation, on the teamwork regarding death and donation, on the satisfaction of bereaved relatives, and on organ donation rates.

Use and monitoring of bromides in epilepsy treatment

Bromides are no longer a mainstay of epilepsy therapy because of the significant toxicity associated with their use and the availability of safer agents. However, bromides occasionally find a niche in the treatment of patients with refractory seizures, particularly in pediatrics. When the decision to utilize this therapy is made, the clinician may be frustrated by the lack of concise, current information regarding bromides. This review provides an update on the mechanism of action, efficacy, pharmacokinetics, dose, and adverse effects of bromides.

Continuing Professional Education and Interacting Variables Affecting Behavioral Change in Practice: Instrument Development and Administration

BACKGROUND

Instruments were developed to measure variables identified by Cervero that evaluate the complex processes and effectiveness of continuing professional education.

METHOD

Content validity was established with a panel of experts. Four studies were conducted to determine reliability. Data were merged to conduct factor analysis.

RESULTS

Reliability was confirmed across studies using Cronbach's alpha. Stability was confirmed in a test-retest study. Factor analysis confirmed instrument items measure the concepts of Cervero's Model.

CONCLUSION

The reliable and valid instruments may be useful for continuing education and staff development nurses to measure the effectiveness of education on behavioral change in practice.

Influence of angiotensin converting enzyme (ACE) genotype on interpretation of diagnostic tests for serum ACE activity

BACKGROUND

The discovery that an insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene influences the circulating concentration of ACE may have implications for the proper use of serum ACE activity measurements in screening for sarcoidosis.

AIM

To determine whether the sensitivity of the serum ACE test improves if ACE genotype is taken into account.

METHODS

A retrospective determination of ACE genotype and clinical diagnosis was done in 54 patients with serum ACE activity above the upper limit of the reference range for the insertion (II) genotype. ACE was measured by radioenzymatic and spectrophotometric techniques, and genotype by PCR.

RESULTS

When serum ACE values determined diagnostically were related to the appropriate genotype-specific reference range, sensitivity and specificity for diagnosis of sarcoidosis were 65-70% and 58% respectively, compared to 47-57% and 77% with a reference range unsegregated for genotype.

CONCLUSION

ACE genotyping may be helpful in determining the diagnostic significance of mildly elevated serum ACE activity in patients with the II and ID genotypes.

Recent advances in the methods of cost-benefit analysis in healthcare. Matching the art to the science

This paper outlines recent advances in the methods of cost-benefit analysis (CBA). Economic evaluations in healthcare can be criticised for, amongst other things, the inappropriate use of incremental cost-effectiveness ratios and the reporting of benefits in terms of cost savings, such as treatment costs averted. Many such economic evaluations are, according to the 'scientific' definition, CBAs. The 'balance-sheet' (or opportunity cost) approach is a form of CBA which can be used to identify who bears the costs and who reaps the benefits from any change. Whilst the next stage in a CBA, as defined in health economics, would require that all costs and benefits be valued in monetary terms, the balance-sheet approach, however, advocates that available monetary values can be augmented by other measures of cost and benefit. As such, this approach, which has a theoretical basis, is proposed as a practical prescription for CBA and highlights the notion that unquantified benefits are important and can be included within CBAs even when monetarisation is not possible. Recent methodological developments in monetary valuation for use in CBA are the development of the technique of willingness to pay, the use of conjoint analysis (CA) to elicit willingness-to-pay (WTP) values and advances in the debate on the inclusion of production gains in CBAs. Whilst acknowledging that there have been developments in each of these areas, it is claimed there has also been progress in using CBA as a framework for evaluation, as reflected by the balance-sheet approach. The paper concludes by stating that almost all types of economic evaluation have an element of the 'cost-benefit' approach in them. The important issue is to focus on the policy question to be addressed and to outline the relevant costs and benefits in a manner which assists the evaluation of welfare changes resulting from changes in healthcare delivery. The focus should not be on moulding a question to fit a hybrid definition of an analytical technique.

Cryptocyanin, a crustacean molting protein: evolutionary link with arthropod hemocyanins and insect hexamerins

Cryptocyanin, a copper-free hexameric protein in crab (Cancer magister) hemolymph, has been characterized and the amino acid sequence has been deduced from its cDNA. It is markedly similar in sequence, size, and structure to hemocyanin, the copper-containing oxygen-transport protein found in many arthropods. Cryptocyanin does not bind oxygen, however, and lacks three of the six highly conserved copper-binding histidine residues of hemocyanin. Cryptocyanin has no phenoloxidase activity, although a phenoloxidase is present in the hemolymph. The concentration of cryptocyanin in the hemolymph is closely coordinated with the molt cycle and reaches levels higher than hemocyanin during premolt. Cryptocyanin resembles insect hexamerins in the lack of copper, molt cycle patterns of biosynthesis, and potential contributions to the new exoskeleton. Phylogenetic analysis of sequence similarities between cryptocyanin and other members of the hemocyanin gene family shows that cryptocyanin is closely associated with crustacean hemocyanins and suggests that cryptocyanin arose as a result of a hemocyanin gene duplication. The presence of both hemocyanin and cryptocyanin in one animal provides an example of how insect hexamerins might have evolved from hemocyanin. Our results suggest that multiple members of the hemocyanin gene family-hemocyanin, cryptocyanin, phenoloxidase, and hexamerins-may participate in two vital functions of molting animals, oxygen binding and molting. Cryptocyanin may provide important molecular data to further investigate evolutionary relationships among all molting animals.

Response-ordering effects: a methodological issue in conjoint analysis

Conjoint analysis is a technique relatively new to the evaluation of health care services in the UK. The technique uses data generated from questionnaires. This paper addresses the issue of response-ordering effects that may result from the ordering of dimensions of benefit within a question. Two questionnaires were given to 216 hospital consultants as part of a priority setting exercise. These were identical other than the ordering of the dimensions within each question. The regression analysis was segmented according to questionnaire type and the coefficients of the segmentation were tested for statistically significant differences. The results show no evidence of ordering effects.

Transmural myocardial blood flow distribution in hypertrophic cardiomyopathy and effect of treatment

Verapamil alleviates symptoms in patients with hypertrophic cardiomyopathy (HCM), but the underlying mechanism of improvement remains speculative. Baseline and dipyridamole myocardial blood flow (MBF) were measured in 15 HCM patients (14 men, 42 +/- 10 years), before and after 4 weeks of verapamil SR 480 mg daily, using 15O labelled water the positron emission tomography (PET). Subendocardial (endo) and subepicardial (epi) MBF was measured in the septum (thickness 25.4 +/- 5.8 mm). Pre-treatment baseline whole heart MBF was 1.02 +/- 0.28 ml/min/g and 1.01 +/- 0.30 ml/min/g on treatment (p = ns). Dipyridamole MBF was 1.39 +/- 0.31 ml/min/g off treatment and 1.23 +/- 0.34 ml/min/g on treatment (p = ns). Coronary flow reserve (dipyridamole/resting MBF) was 1.45 +/- 0.52 and 1.30 +/- 0.51, respectively (p = ns). At baseline, the septal endo/epi MBF ratio was uniform off and on treatment (1.13 +/- 0.18 vs 1.18 +/- 0.21, p = ns). Before treatment, the endo/epi ratio following dipyridamole decreased to 0.93 +/- 0.24 (p < 0.01 vs baseline) and 5/15 (33%) patients had a ratio < 0.8 which would suggest subendocardial underperfusion. During treatment, the endo/epi ratio following dipyridamole was no more different from baseline (1.06 +/- 0.24, p = ns vs baseline) and 2/14 (14%) patients had an endo/epi < 0.8. PET can be successfully used to determine transmural MBF in vivo in patients with hypertrophied ventricles. Despite symptomatic improvement, high dose verapamil therapy does not increase total MBF in patients with HCM but may improve septal transmural MBF distribution during dipyridamole in some patients.

Using conjoint analysis to take account of patient preferences and go beyond health outcomes: an application to in vitro fertilisation

There has been an assumption in the health economics literature that health outcomes are all that need to be considered when attempting to measure the benefits from health care interventions. This is most evident in the development of the quality adjusted life year (QALY) approach to benefit assessment. This paper challenges this view and considers the technique of conjoint analysis (CA) as a methodology for both taking account of patient preferences and considering attributes beyond health outcomes. The technique is applied to in vitro fertilisation. CA is shown to be sensitive to considering health outcomes, nonhealth outcomes and process attributes. It is also shown to be internally consistent and internally valid. The paper demonstrates the application of CA to estimating willingness to pay indirectly. It is argued that benefit assessment within health economics should extend beyond health outcomes and future research should investigate more thoroughly the potential application of CA in this area. However, methodological issues need addressing before the instrument becomes an established evaluative instrument.