Epidemiology of viral infections and evaluation of the potential benefit of OM-85 BV on the virologic status of children attending day-care centers

Viral investigations were performed during 4 winter seasons (88/89, 89/90, 92/93, 93/94) in children attending day-care centers (DCCs) in the Rhône Département in eastern France. Over the total observation period of 4 winter seasons, 780 children were screened with a nasal swab for the presence of viruses. Of those, 230 (29.5%) had a positive viral culture. The viruses identified were respiratory syncytial virus (RSV), influenza A and B virus, parainfluenza virus, coronavirus, rhinovirus, adenovirus and enterovirus. During that time, 83 epidemic events in 47 DCC were recorded. A particular virus was judged to be causally related to an epidemic if the identical virus was isolated in > or = 3 children during the same outbreak of respiratory diseases. Thus, in 51 cases (61.4%) of all epidemics, the following viruses were responsible for an epidemic: RSV (n = 23), coronavirus (n = 10) (only during the season of 1993-1994), influenza A virus (n = 6), rhinovirus (n = 4), enterovirus (n = 4), adenovirus (n = 3) and parainfluenza virus (n = 1). Except for the somewhat surprising accumulation of coronavirus epidemics during the winter of 1993-1994, there were only minor seasonal variations from one year to another. As expected, RSV accounted for about one third of all respiratory tract infections in children attending DCCs and was therefore the most important single causative agent. These results are compared with data from children who did not attend a DCC and were cared for in a private practice.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the effect of phosphodiesterase inhibitors on mortality in chronic heart failure patients. A meta-analysis

We examined the influence of phosphodiesterase inhibitors (PDIs) on mortality in patients with overt chronic heart failure. A total of 13 randomised, placebo-controlled trials of PDIs involving 2808 patients were selected. Meta-analysis, using data for all patients, showed that there was a non-significant (P = 0.16) increase of about 17% in the mortality rate of patients receiving a PDI [odds ratio (OR) 1.17, 95% confidence interval (CI) 0.94-1.46]. However, the observed treatment effects were found to be heterogeneous due to the results from the trials on vesnarinone. The heterogeneity became non-significant (P = 0.77) when these trials were removed, and a significant increase in the mortality rate was observed under treatment with the other PDIs (OR 1.41, 95% CI 1.11-1.79). In the subgroups of patients with or without additional vasodilator (VD) treatment, similar results were observed (PDI with VD: OR 1.3, 95% CI 1.03-1.7; PDI without VD: OR 2.04, 95% CI 1.1-3.8). These results indicate that PDIs (with the exception of vesnarinone) should not be prescribed for long-term use in patients with overt chronic heart failure. Additional vasodilator treatment in patients receiving PDIs for chronic heart failure does not explain the increased mortality seen with PDIs. This toxicity must, therefore, arise by other mechanisms. Further experimental and clinical evaluation is needed to confirm the beneficial influence of vesnarinone on survival in chronic heart failure patients and to identify the mechanism(s) differentiating this agent's therapeutic effect from that of other PDIs.

The role of an initial single-blind placebo period in phase I clinical trials

The effect of an initial single-blind placebo period in a phase I clinical trial was assessed in 12 volunteers who underwent five weekly treatment periods, consisting of treatment on the first day and a six-day wash-out period. An initial single-blind placebo period was followed by three different single doses of a platelet-aggregation factor inhibitor and another placebo period, under a double-blind Latin square design. Reports of abnormal symptoms were collected using a questionnaire designed by our group. A total of 13 abnormal symptoms were reported during the first period and only nine for the following four periods, indicating a clear placebo period effect. These preliminary results suggest that an initial single-blind period may be usefully included in phase I clinical trials.

OM-85 BV: primary versus secondary prevention

Recurrent upper respiratory tract infections in children have an important socioeconomic impact, with consequences on both the quality of life of the children, the possible medical sequelae and the inherent direct and indirect costs. The possibility to prevent these infections is limited in the absence of specific vaccines against microorganisms responsible for most of the respiratory tract infections (i.e. respiratory syncitial virus, adenovirus, rhinovirus). Immunoactive bacterial extracts that stimulate the nonspecific component of the immune system may protect against a large variety of microorganisms that enter the body by the oral and respiratory pathway; they may, therefore, play an important role with regard to this preventive action. OM-85 BV is an IBE that has been used in children who suffer from repeated infections to prevent the occurrence of new episodes (secondary prevention). In this condition, the drug has been shown to be effective in protecting children against recurrent airway infections. Its use as a primary preventive agent to prevent the development of repeated infections in children attending day-care centers (a very high-risk environment for repeated infections), however, did not show a similar efficacy. The risk of having > or = 4 episodes of upper respiratory tract infections over a period of 7.5 months was 26.7% in the verum group and 33.8% in the placebo group (relative risk 0.79, confidence interval 0.59-1.06]. In an exploratory analysis concentrating on the 3-month treatment period, however, a 48% reduction of the risk of presenting > or = 3 episodes was observed. Furthermore, this exploratory analysis showed a strong correlation between drug efficacy and age of the children.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophysiologic effects of a potassium channel activator (pinacidil) on repolarization parameters in healthy volunteers: a surface ECG study

About a quarter to a third of patients receiving pinacidil, a new cyanoguanidine vasodilator, show ECG changes, in particular T-wave modifications that sometimes mimic myocardial ischemia. To investigate these changes, we performed a randomized placebo-controlled trial in 10 carefully selected, healthy subjects who received single oral doses of either pinacidil (25 mg), quinidine (330 mg), and placebo. Quinidine, which induces specific modifications to the surface ECG signal, was used as an internal control. The complete experimental design involved five consecutive administrations of the drugs in random order: pinacidil (twice), quinidine (twice), and placebo (once), separated by a week-long washout period. Electrophysiologic data acquisition and signal analysis were performed with the Lyon vectocardiographic processing system. Pinacidil decreased T-wave amplitude (-0.26 +/- 0.1 mV) significantly as compared with placebo (-0.14 +/- 0.06 mV), but did not change the duration of the T-wave. Although the cardiac rate increased with pinacidil, the QTc interval remained constant. Conversely, quinidine did not modify the RR interval but significantly increased duration of the T-wave (+67 +/- 20 ms) and QTc interval (+53 +/- 13 ms) as compared with placebo (+17 +/- 13 and +18 +/- 11 ms). In addition, no specific ischemic changes to the T-loop were observed with pinacidil. The modifications to the surface ECG signal caused by pinacidil appear to be drug-specific and related to its electrophysiologic properties rather than involving any ischemic mechanism. Such an approach may be useful for describing morphologic ECG changes caused by new drugs and identifying possible underlying electrophysiologic mechanism(s), which should then be confirmed in further studies.

Erythropoietin structure-function relationships: high degree of sequence homology among mammals

To investigate structure-function relationships of erythropoietin (Epo), we have obtained cDNA sequences that encode the mature Epo protein of a variety of mammals. A first set of primers, corresponding to conserved nucleotide sequences between mouse and human DNAs, allowed us to amplify by polymerase chain reaction (PCR) intron 1/exon 2 fragments from genomic DNA of the hamster, cat, lion, dog, horse, sheep, dolphin, and pig. Sequencing of these fragments permitted the design of a second generation of species-specific primers. RNA was prepared from anemic kidneys and reverse-transcribed. Using our battery of species-specific 5' primers, we were able to successfully PCR-amplify Epo cDNA from Rhesus monkey, rat, sheep, dog, cat, and pig. Deduced amino acid sequences of mature Epo proteins from these animals, in combination with known sequences for human, Cynomolgus monkey, and mouse, showed a high degree of homology, which explains the biologic and immunological cross-reactivity that has been observed in a number of species. Human Epo is 91% identical to monkey Epo, 85% to cat and dog Epo, and 80% to 82% to pig, sheep, mouse, and rat Epos. There was full conservation of (1) the disulfide bridge linking the NH2 and COOH termini; (2) N-glycosylation sites; and (3) predicted amphipathic alpha-helices. In contrast, the short disulfide bridge (C29/C33 in humans) is not invariant. Cys33 was replaced by a Pro in rodents. Most of the amino acid replacements were conservative. The C-terminal part of the loop between the C and D helices showed the most variation, with several amino acid substitutions, deletions, and/or insertions. Calculations of maximum parsimony for intron 1/exon 2 sequences as well as coding sequences enabled the construction of cladograms that are in good agreement with known phylogenetic relationships.

An effect model for the assessment of drug benefit: example of antiarrhythmic drugs in postmyocardial infarction patients

An effect model is a function that defines the relationship between the clinical efficacy of a treatment and specific covariates. The simplest effect model defines the probability of failure in treated patients as a linear function of the probability for these patients if they received no treatment. We used this approach to explore the effects of Class I antiarrhythmic agents in patients after myocardial infarction. Evidence from one large trial, the Cardiac Arrhythmic Suppression Trial (CAST), and the pooling of data from several smaller trials suggests that these agents have harmful effects in postmyocardial infarction patients. The relevance of results from pooled data is dependent on the homogeneity of the trials and is assessed by a heterogeneity test that is dependent on the analytical method used, i.e., odds ratio or rate difference methods, which correspond to two different effect models. We have developed an effect model that considers both iatrogenic effects of these drugs, i.e., depression of ventricular function and arrhythmogenic effects. When applied to the data from 13 published trials (including CAST), we found that these drugs may be beneficial in high-risk patients (with a 1-year mortality rate of > or = 15%) and that the background lethal iatrogenic effect is likely to affect low- and very low-risk patients (1-year mortality rate of < or = 5%). The accuracy of the proposed model was confirmed with use of the results from the recent CAST II study.

Erythropoietin structure-function relationships. Mutant proteins that test a model of tertiary structure

On the basis of its primary sequence and the location of its disulfide bonds, we propose a structural model of the erythropoietic hormone erythropoietin (Epo) which predicts a four alpha-helical bundle motif, in common with other cytokines. In order to test this model, site-directed mutants were prepared by high level transient expression in Cos7 cells and analyzed by a radioimmuno assay and by bioassays utilizing mouse and human Epo-dependent cell lines. Deletions of 5 to 8 residues within predicted alpha-helices resulted in the failure of export of the mutant protein from the cell. In contrast, deletions at the NH2 terminus (delta 2-5), the COOH terminus (delta 163-166), or in predicted interhelical loops (AB: delta 32-36, delta 53-57; BC: delta 78-82; CD: delta 111-119) resulted in the export of immunologically detectable Epo muteins that were biologically active. The mutein delta 48-52 could be readily detected by radioimmunoassay but had markedly decreased biological activity. However, replacement of each of these deleted residues by serine resulted in Epo muteins with full biological activity. Replacement of Cys29 and Cys33 by tyrosine residues also resulted in the export of fully active Epo. Therefore, this small disulfide loop is not critical to Epo's stability or function. The properties of the muteins that we tested are consistent with our proposed model of tertiary structure.

Polychemotherapy in advanced non small cell lung cancer: a meta-analysis

We did a meta-analysis of all published polychemotherapy vs supportive care clinical trials in patients with non-resectable non small cell lung cancer. 7 studies with more than 700 patients were selected. We used the number of deaths at 3, 6, 9, 12, and 18 months as the endpoints because we were unable to obtain all the individual data. Our analysis showed a reduction in mortality during the first 6 months with polychemotherapy. Although small, this increase in survival, together with an improved quality of life, suggests that polychemotherapy should be recommended for patients with non-resectable non small cell lung cancer.

[Calcium channel antagonists and myocardial ischemia or ischemia/reperfusion]

Many theoretical and experimental studies suggest that calcium antagonists drugs should be useful in pathological situations of myocardial ischemia or ischemia/reperfusion. This therapeutic model was tested in controlled trials of angina, post-infarction and cardiac surgery. The authors undertook a meta-analysis of these trials using the occurrence of myocardial infarction or death as criteria of judgement. No long-term benefits seem to be associated with the dihydropyridines such as nifedipine and nicardipine in anginal patients. In unstable angina, betablockers seem to be more effective but the difference is not statistically significant. In the post-infarction period, nifedipine does not reduce the risk of recurrence of myocardial infarction and may even increase the mortality by 15%, though this was not significant in the 9,055 patients studied (p = 0.08). Verapamil and diltiazem globally reduce the risk of recurrent infarction by 21% (p = 0.009) but not mortality (p = 0.52). Because of the small numbers of patients and the low prevalence of observed events, no useful conclusions can be drawn from studies of calcium antagonists in cardiac surgery. The results of the validation of the therapeutic model "calcium antagonists in pathological situation of myocardial ischemia or ischemia/reperfusion" does not justify the labels "anti-ischemics" or "cardio protectors" often applied to the calcium antagonists.

Pharmacodynamic model of the haemodynamic effects of pinacidil in normotensive volunteers

The concentration-effect relationships of pinacidil, a peripheral vasodilator, have been measured in 12 healthy adults who received placebo or pinacidil 25 mg daily for 1 week in a cross-over experiment. Diastolic blood pressure (DBP) and heart rate (HR) were recorded and blood samples were taken on days 1 and 7. Plasma drug concentration-time data were fitted by a biexponential function with zero-order input. The pharmacokinetic model was incorporated into a combined pharmacokinetic-dynamic model (PK-PD) using the Hill equation, which has three parameters: n, the sigmoidicity parameter, Emax the maximum effect and EC50 the concentration which gives 50% of Emax. For delta DBP, the parameter medians were estimated as n = 5, EC50 = 44.6 ng.ml-1 and Emax = 13.5 mmHg. A hysteresis loop was found when delta HR was plotted against concentration, which could be fitted by a linear effect compartment model. Simulations showed that experimental delta DBP points on Day 7 could be predicted from a simulated curve computed by the model using parameters estimated on Day 1. Using the simulation, it was possible to suggest an optimal dosage regimen for pinacidil tablets.

Treatment with growth hormone-releasing hormone (GHRH) 1-44 in children with idiopathic growth hormone deficiency: a randomized double-blind dose-effect study. The GHRH European Multicenter Study (GEMS) Group

One hundred and eleven pre-pubertal children (70 boys, 41 girls, aged 2.5 to 14.3 years) with growth failure (height 2 SD below the mean for chronological age (CA) and height velocity (HV) below the 10th percentile for bone age) due to idiopathic growth hormone deficiency (peak plasma GH < 20 mUI/1 to two standard provocative tests) were treated with GHRH 1-44 NH2. Patient stratification in two classes was performed according to body weight; in each class, patients were randomly allocated to one of seven GHRH doses, from 30 to 300 micrograms/day. GHRH was injected subcutaneously, every evening, for six months in a double-blind fashion. No relationship was found between the absolute or incremental HV during treatment and the dose (range from 1.3-23.1 micrograms/kg/day) of GHRH. However, HV (cm/year) increased from 3.8 +/- 0.1 (mean +/- SEM) before treatment to 6 +/- 0.2 during six months treatment and 47 patients (42%) increased their HV up to at least the mean normal HV for bone age (catch-up growth). Low titer antibodies to GHRH were found in 19 patients (17.1%) at six months; no adverse effect was observed. Our results suggest that patients showing catch-up growth were older, had a height closer to the mean for chronological age and a slower pre-treatment height velocity. Failure to demonstrate a relationship between GHRH dose and changes in growth velocity might be explained by the combination of a placebo effect, insufficient frequency of GHRH administration and heterogeneity of the population.

Low molecular weight heparin in prevention of perioperative thrombosis

OBJECTIVE

To determine whether prophylactic treatment with low molecular weight heparin reduces the incidence of thrombosis in patients who have had general or orthopaedic surgery.

DESIGN

Meta-analysis of results from 52 randomised, controlled clinical studies (29 in general surgery and 23 in orthopaedic surgery) in which low molecular weight heparin was compared with placebo, dextran, or unfractionated heparin.

SUBJECTS

Patients who had had general or orthopaedic surgery.

INTERVENTION

Once daily injection of a low molecular weight heparin compared with placebo, dextran, or unfractionated heparin.

MAIN OUTCOME MEASURES

Incidence of deep venous thrombosis, pulmonary embolism, major haemorrhages, and death.

RESULTS

The results confirm that low molecular weight heparins are more efficacious for the prophylactic treatment of deep venous thrombosis than placebo (common odds ratio 0.31, 95% confidence interval 0.22 to 0.43; p < 0.001) and dextran (0.44, 0.30 to 0.65; p < 0.001). The results suggest that low molecular weight heparins are also more efficacious than unfractionated heparin (0.85, 0.74 to 0.97; p = 0.02), with no significant difference in the incidence of major haemorrhages (1.06, 0.93 to 1.20; p = 0.62).

CONCLUSIONS

Low molecular weight heparins seem to have a higher benefit to risk ratio than unfractionated heparin in preventing perioperative thrombosis. However, it remains to be shown in a suitably powered clinical trial whether low molecular weight heparin reduces the risk of fatal pulmonary embolism compared with heparin.

Surrogate endpoints: a basis for a rational approach

In clinical trials, the clinical endpoint is often replaced by an intermediate endpoint, known in some instances as a "surrogate" endpoint. The reasons for the substitution are often both practical and financial. At present, no theoretical basis or practical guidelines exist to help in the choice of surrogate endpoints. An approach is proposed here, based on three provisos which can be verified using one of a series of equations, if sufficient data on the pathophysiology and epidemiology of the disease are available. It is shown that even a strong statistical correlation is not a sufficient criterion for the definition of a surrogate endpoint. It is apparent that results obtained with the commonly used "surrogate" endpoints should be cautiously considered, and that the assessment of treatments should, when possible, be based on clinical rather than intermediate endpoints.

[Technique for measuring the atheroma volume in men]

The evaluation of the impact of therapy on the evolution of atherosclerotic lesions or restenosis after angioplasty requires the use of techniques of vascular imaging. The reference invasive method is digital angiography although it does not provide data on the arterial wall thickness. This parameter can be approached however by intravascular ultrasound imaging, a technique which has a number of important practical limitations. Of the non-invasive techniques available, Doppler ultrasonography is the only one that can be used in clinical trials. Nuclear magnetic resonance imaging is the object of much research and is without doubt the technique of the future. The choice of model of atherosclerosis influences that of the imaging technique: cineangiography for coronary arteries, digital angiography or Doppler ultra sonography for lower limb arteries and Doppler ultrasonography for the carotid arteries. Interpretation of angiography is now performed quantitatively by videodensitometry. Interpretation of other techniques should be performed by a second independent observer and "blinded" with respect to the order in which the investigations were performed and to the treatment administered. The criteria of judgment may be qualitative (progression, stabilisation, regression) or quantitative, the latter having a number of advantages over the former. Of the quantitative criteria, the percentage stenosis, though widely used, does not fully answer the question posed, and neither does the diameter of the stenosis. The volume of the arterial lumen calculated from videodensitometric data would seem to be the best, by its sensitivity and additivity, current angiographic parameter.(ABSTRACT TRUNCATED AT 250 WORDS)