Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “crossover frequency”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1983

Enzymatic formation of biparental figure-eight molecules from plasmid DNA and their resolution in E. coli.

A key intermediate in general genetic recombination is a structure in which two double-stranded DNA molecules are covalently linked by a single-strand crossover characteristic of a Holliday junction. When the DNA molecules are circular, the recombinant structures take the form of a figure eight. We have used purified E. coli enzymes to construct biparental figure-eight DNA molecules in vitro from the DNA of two partially homologous plasmids. When purified figure-eight structures are transfected into recA- E. coli cells, they are resolved to produce monomeric or dimeric plasmid progeny, apparently by the cutting and joining of the Holliday crossover. The maturation of figure-eight molecules in bacteria is characterized by the formation and recovery of both parental and recombinant types, cross-over at a frequency of up to 50% and the capability for mismatch repair at regions of hybrid DNA. In these three regards, the products of figure-eight maturation resemble recombinant chromosomes formed at meiosis. These observations show that biparental figure eights behave as recombination intermediates that can be resolved into mature recombinants without need for a functional recA+ gene product.

Bacterial Proteins↗
PubMed1998

Conventional and spectral power analysis of all-night sleep EEG after subchronic treatment with paroxetine in healthy male volunteers.

Paroxetine is a selective and potent serotonin reuptake inhibitor with reported antidepressant properties. Since changes in the regular sleeping pattern were described as side effects under treatment with paroxetine, the impact of the drug on the sleep architecture is of major interest. The present study addressed the question of subchronic effects of paroxetine medication (30 mg/day) in eight healthy male volunteers in a double blind, placebo-controlled crossover-design. Conventional sleep EEG parameters and additionally computed spectral power analysis based on FFT of 20-s time epochs in the delta, theta, alpha, beta and gamma frequency range for different sleep stages after 4 weeks of treatment were investigated. Subchronic paroxetine administration in healthy subjects led to a prolonged REM latency and a decrease in the number of REM phases, whereas sleep efficiency, total sleep time, sleep onset latency, number of awakenings, and awake during sleep period time were not altered by paroxetine medication. Moreover, we could not detect any alterations of the spectral power values in certain frequency bands during NREM or REM sleep following subchronic paroxetine medication.

Adult↗
PubMed1992

Pharmacokinetics and pharmacodynamics of oral diazepam: effect of dose, plasma concentration, and time.

Eleven healthy subjects received single oral doses of placebo, 2 mg diazepam, 5 mg diazepam, and 10 mg diazepam in a randomized four-way crossover study. Plasma diazepam levels, the Digit Symbol Substitution Test (DSST), and fraction of total electroencephalographic (EEG) amplitude falling in the sigma plus beta (13 to 31 Hz) frequency range were determined during the 12 hours after drug administration. Peak plasma diazepam concentration and area under the 12-hour curve were proportional to dose; time of peak was independent of dose. Baseline percentage of EEG amplitude falling in the 13 to 31 Hz range averaged 15.7% and did not differ among the four trials. The percentage of EEG amplitude falling in the 13 to 31 Hz range did not change over baseline with placebo or 2 mg diazepam but was increased 1/4 to 2 1/2 hours after 5 mg diazepam, (maximum, +7.3%) and 3/4 to 12 hours after 10 mg diazepam (maximum, +15.2%). The increase in the percentage of EEG amplitude falling in the 13 to 31 Hz range was highly correlated with plasma diazepam concentration. DSST scores for placebo and 2 mg diazepam were nearly identical. DSST decrements with 5 and 10 mg diazepam paralleled and were correlated with the changes in the percentage of EEG amplitude falling in the 13 to 31 Hz range and with plasma diazepam levels. Thus the EEG analysis provides objective quantitation of benzodiazepine central nervous system effects, in turn reflecting plasma levels and other clinical measures.

Administration, Oral↗
PubMed1980

Principal and differential effects of haoperidol and placebo treatments upon speech disfuluencies in stutterers.

Fourteen stutterers completed a double-blind crossover study of the effects of Haloperidol and Placebo treatments upon their speech disfluencies. Although clearly not clinically effective, Haloperidol had a statistically significant effect upon reducing disfluency frequency and increasing speaking rate. For most subjects, drug-related reductions in disfluency severity resulted from a decrement in whole-word and phrase repetition, interjection, and revision-type disfluencies rather than from fewer part-word (elemental) repetitions and prolongations of sound or of silence. Neurotic personality profile correlated positively with an overall placebo effect, and there was a positive correlation between abnormal EEG and the drug effect. These findings are discussed in light of the nature of speech disfluency and stuttering and Haloperidol's biochemical and behavioral actions.

Adolescent↗
PubMed2004

Dynamics of HIV-1 recombination in its natural target cells.

Genetic recombination is believed to assist HIV-1 diversification and escape from host immunity and antiviral therapies, yet this process remains largely unexamined within the natural target-cell populations. We developed a method for measuring HIV-1 recombination directly that employs reporter viruses bearing functional enhanced yellow fluorescent protein (YFP) and enhanced cyan fluorescent protein (CFP) genes in which recombination produces a modified GFP gene and GFP fluorescence in the infected cells. These reporter viruses allow simultaneous quantification of the dynamics of HIV-1 infection, coinfection, and recombination in cell culture and in animal models by flow-cytometric analysis. Multiround infection assays revealed that productive cellular coinfection was subject to little functional inhibition. As a result, generation of recombinants proceeded according to the square of the infection rate during HIV-1 replication in T lymphocytes and within human thymic grafts in severe combined immunodeficient (SCID)-hu (Thy/Liv) mice. These results suggest that increases in viral load may confer a compounding risk of virus escape by means of recombinational diversification. A single round of replication in T lymphocytes in culture generated an average of nine recombination events per virus, and infection of macrophages led to approximately 30 crossover events, making HIV-1 up to an order of magnitude more recombinogenic than recognized previously and demonstrating that the infected cell exerts a profound influence on the frequency of recombination.

Animals↗
PubMed2003

Measuring the condensate fraction of rapidly rotating trapped boson systems: off-diagonal order from the density profile.

We demonstrate a direct connection between the density profile of a system of ultracold trapped bosonic particles in the rapid-rotation limit and its condensate fraction. This connection can be used to probe the crossover from condensed vortex-lattice states to uncondensed quantum-fluid states that occurs in rapidly rotating boson systems as the particle density decreases or the rotation frequency increases. We illustrate our proposal with a series of examples, including ones based on models of realistic finite trap systems, and comment on its application to freely expanding boson density profile measurements.

Journal Article↗
PubMed2005

Quantum critical behavior near a density-wave instability in an isotropic fermi liquid.

We study the quantum critical behavior in an isotropic Fermi liquid in the vicinity of a zero-temperature density-wave transition at a finite wave vector qc. We show that, near the transition, the Landau damping of the soft bosonic mode yields a crossover in the fermionic self-energy from Sigma(k,omega) approximately Sigma(k) to Sigma(k,omega) approximately Sigma(omega), where k and omega are momentum and frequency. Because of this self-generated locality, the fermionic effective mass diverges right at the quantum critical point, not before; i.e., the Fermi liquid survives up to the critical point.

Journal Article↗
PubMed2004

Shock on T versus direct current voltage for induction of ventricular fibrillation: a randomized prospective comparison.

VF is induced during ICD implantation to determine efficacy of therapy. Establishing the best clinical method of induction of VF would potentially be beneficial in reducing the number of induction attempts and reducing the frequency of inadvertent induction of VT. Commonly used methods to induce VF include shock in the T wave vulnerable period (T shock) and high frequency stimulation. This study compared the efficacy of T shock with a new induction method using a 9-V DC pulse. The study was a randomized, prospective, case crossover trial in patients receiving ICDs. VF was induced by T shock and DC in a randomized sequence during an ICD implant. VF was induced at least four times in each patient (two T shocks and two DC inductions) and with each induction; attempts were continued with modifications until successful. A paired evaluation between the T shock/DC induction was performed in 37 patients (28 men, age 64 +/- 12 years) with a left ventricular ejection fraction of 0.40 +/- 0.20. Arrhythmia indications were VT (n = 23), VF (n = 10), and VT/VF (n = 4). Drug therapy included amiodarone (n = 10), metoprolol (n = 6), digoxin (n = 1), and lidocaine (n = 1). The average T shock voltage was 207.0 +/- 16.1 V. The S1 cycle drive length was consistently 400 ms, and the mean S2 coupling interval was 317.8 +/- 19.6 ms. The length of time DC applied averaged 3.8 +/- 1.4 seconds. A total of 148 episodes of VF were included in the analysis. T shock induced VF with a cycle length of 213.5 +/- 35.1 ms, and DC induced VF with a cycle length of 214.6 +/- 34.5 ms (P = 0.86). Although VF was eventually induced for each randomization, the number of attempts required were dependent on the method of induction. The successful DC first attempt VF induction rate was 96%, with three patients requiring two attempts during one of the DC inductions. T shock had a 68% first attempt success rate with 21 patients requiring multiple T shocks to induce VF. All nine female patients had at least one unsuccessful first attempt T shock, which contributed to an overall unsuccessful first attempt induction rate significantly higher in women then men (36.1% vs 12.5%, P = 0.001). A constant DC voltage induction of VF may be more effective than T shock for induction of VF in a clinical setting because it reduces the number of attempts required to induce VF. By either method, VF appears to be more difficult to induce in women. DC induction has the advantage of simple programming of only duration of stimulation. These findings have implications particularly for ICD implantation with conscious sedation.

Amiodarone↗
PubMed1990

Vancomycin-induced histamine release and "red man syndrome": comparison of 1- and 2-hour infusions.

Vancomycin-induced "red man syndrome" (RMS) is mediated in part by histamine release, and its severity is correlated with the area under the plasma histamine concentration-time curve. Ten adult male volunteers participated in a randomized, double-blind, two-way crossover trial (1-week washout interval between regimens) to determine the effect of 1- and 2-h infusions of vancomycin (1.0 g) on histamine release and on the frequency and severity of RMS. The severity of RMS was classified a priori as mild, moderate, or severe from a combined score of pruritus and extent of erythema. Serial concentrations of histamine in plasma and concentrations of vancomycin in serum were measured at baseline and during and after each infusion. Of 10 subjects, 8 had evidence of RMS during the 1-h infusion (3 mild, 3 moderate, and 2 severe), whereas only 3 of the 10 subjects (all mild) had RMS during the 2-h infusion (P less than 0.05). The 1-h infusion was associated with a significantly greater peak concentration of histamine in plasma (1.8 +/- 0.7 versus 1.0 +/- 0.3 ng/ml, P = 0.004) and a greater total release of histamine (74.3 +/- 54.1 versus 36.4 +/- 22.6 ng.min/ml, P = 0.017) than was the 2-h infusion. These data suggest that administration of vancomycin over 2 h reduces the frequency and severity of RMS and the amount of histamine released compared with those after a 1-h infusion in healthy volunteers.

Adult↗
PubMed1999

Long-term multicenter experience with vagus nerve stimulation for intractable partial seizures: results of the XE5 trial.

OBJECTIVE: Intermittent stimulation of the left cervical vagus nerve trunk (VNS) with the NeuroCybernetic Prosthesis (NCP) is emerging as a novel adjunct in the management of medically refractory epilepsy. We review the safety and efficacy of VNS 1 year after completion of the E05 study, the largest controlled clinical trial of VNS to date. METHODS: One hundred and ninety-nine patients with intractable epilepsy and at least 6 complex partial or secondarily generalized seizures per month enrolled in a randomized, double-blinded, partial crossover trial of high versus low parameters of stimulation (E05). After 3 months, all patients received high stimulation during an open-label, nonblinded extension trial (XE5). Seizure frequency, adverse events and multiple physiologic variables were monitored at regular intervals. RESULTS: At 3 months, the mean reduction in seizure frequency among patients receiving high stimulation during E05 was 28%. Of the 199 subjects participating in this acute-phase trial, 195 continued in the long-term protocol. Among the latter patients, 21 subsequently exited the study due to lack of efficacy, and 2 others died from causes unrelated to VNS. Complete data were obtained for 164 of the remaining subjects. Using a declining N analysis, the mean and median reduction in seizure frequency at 15 months was 37 and 45%, respectively. A last visit carried forward analysis, which controls for dropouts and incomplete follow-up, yielded comparable results (34 and 45%, respectively), indicating little potential for selection bias. At 15 months, 39% of the subjects had a greater than 50% reduction in seizures, including 21% who had a greater than 75% reduction, and 2% have remained seizure free. Few serious adverse events, physiological perturbation or device failures were reported. CONCLUSIONS: The long-term multicenter safety, efficacy, feasibility and tolerability of VNS, as well as the durability of the NCP device have been confirmed. Unlike chronic therapy with antiepileptic medication, the efficacy of VNS is maintained during prolonged stimulation, and overall seizure control continues to improve with time.

Adult↗
PubMed1976

A double-blind crossover comparison of Orudis (ketoprofen) and indomethacin in the treatment of rheumatoid arthritis.

Twenty-three patients with rheumatoid arthritis participated in a double-blind crossover investigation of ketoprofen (Orudis) and indomethacin. Ratings which assessed the degree of joint involvement showed consistently greater improvement with Orudis, and side-effects occurred with less frequency. The majority of patients expressed a definite preference for Orudis.

Arthritis, Rheumatoid↗
PubMed1988

Systemic interferon therapy of multiple sclerosis: the pros.

The rationale for the use of interferon (IFN) in the treatment of multiple sclerosis (MS) is based on its recognized antiviral and immunomodulating actions. The pathogenesis of MS is generally believed to be due to an immunologic response in a genetically predisposed individual, localized within the CNS white matter, and triggered by exposure to an environmental agent such as a virus. In a randomized, double-blind, placebo-controlled, crossover trial of systemic natural alpha IFN in 24 patients with exacerbating-remitting MS, patients with a strictly exacerbating-remitting course showed a reduction in the frequency and severity of exacerbations, while those with exacerbations superimposed upon a chronic progressive course did not benefit from this treatment, primarily because of side effects that included fever, malaise, and fatigue. Since the performance of this study, it has been shown that the preparation of natural human alpha interferon used in this trial may lead to side effects in some individuals through the production of immune complexes (ICs). These ICs were due to the generation of antibodies reacting with residual Sendai virus proteins used in the preparation of the IFN, and retained in the final formulation. The encouraging results of this and other preliminary studies of alpha or beta IFN but not gamma IFN therapy in MS, coupled with the current availability of more highly purified interferon preparations, warrants further clinical trials of IFN in MS, focusing on beta interferon preparations in particular.

Adult↗
PubMed1984

[Intravenous theophylline therapy. Effect of solubilizers on the incidence of adverse local effects in the area of infusion?].

The frequency and intensity of discomfort and pain at the site of injection during intravenous infusion of theophylline sodium glycinate and theophylline ethylenediamine were compared in a single blind crossover study on 6 healthy adult volunteers. The preparation containing theophylline sodium glycinate was significantly better tolerated than theophylline ethylenediamine.

Adult↗
PubMed1998

Meta-analysis of the effect of insulin lispro on severe hypoglycemia in patients with type 1 diabetes.

OBJECTIVE: A precise time-action profile of insulin lispro (Humalog) at mealtime may reduce the incidence of severe hypoglycemia. Because it is a rare complication, we performed a cumulative meta-analysis to compare the frequency of severe hypoglycemia during insulin lispro and human regular insulin therapy in type 1 diabetic patients. RESEARCH DESIGN AND METHODS: The analysis included eight large multi-center clinical trials, three with parallel and five with crossover designs. The studies included 2,576 type 1 diabetic patients in total, with 2,327 receiving insulin lispro and 2,339 receiving regular human insulin, representing > 1,400 patient-years of insulin therapy Severe hypoglycemia was defined as coma or requiring glucagon or intravenous glucose. The patients received either NPH or ultralente as their basal insulin and insulin lispro or regular human insulin before each meal. RESULTS: Seventy-two patients (3.1%) had a total of 102 severe hypoglycemic episodes during insulin lispro therapy compared with 102 patients (4.4%) with a total of 131 episodes during regular human insulin therapy (P=0.024). CONCLUSIONS: The results of this meta-analysis demonstrate that in type 1 diabetic patients, the frequency of severe hypoglycemia can be reduced by taking insulin lispro as compared with regular human insulin therapy.

Clinical Trials as Topic↗
PubMed2000

Repaglinide acutely amplifies pulsatile insulin secretion by augmentation of burst mass with no effect on burst frequency.

OBJECTIVE: Repaglinide is a new oral hypoglycemic agent that acts as a prandial glucose regulator proposed for the treatment of type 2 diabetes by stimulating insulin secretion. The aim of this study was to explore actions of repaglinide on the rapid pulsatile insulin release by high-frequency insulin sampling and analysis of insulin-concentration time series. RESEARCH DESIGN AND METHODS: We examined 8 healthy lean male subjects in a single-dose double-blind placebo-controlled crossover design. After the subjects underwent an overnight fast, blood sampling was initiated and continued every minute for 120 min. After 40 min, a single dose (0.5 mg) of repaglinide or placebo was given. Serum insulin-concentration time series were assessed by deconvolution analyses and the regularity statistic by approximate entropy (ApEn). RESULTS: Average insulin concentration was increased after repaglinide administration (basal vs. stimulated period, P values are placebo vs. repaglinide) (25.1 +/- 3.6 vs. 33.5 +/- 4.1 pmol/l, P < 0.001). Insulin secretory burst mass (15.8 +/- 2.2 vs. 19.6 +/- 2.8 pmol x l(-1) x pulse(-1), P = 0.02) and amplitude (6.1 +/- 0.9 vs. 7.7 +/- 1.2 pmol x l(-1) x min(-1), P = 0.008) were augmented after repaglinide administration. A concomitant trend toward an increase in basal insulin secretion was observed (2.5 +/- 0.3 vs. 3.2 +/- 0.4 pmol x l(-1) x min(-1), p = 0.06), while the interpulse interval was unaltered (6.8 +/- 1.0 vs. 5.4 +/- 0.4 min/pulse, P = 0.38). ApEn increased significantly after repaglinide administration (0.623 +/- 0.045 vs. 0.670 +/- 0.034, P = 0.04), suggesting less orderly oscillatory patterns of insulin release. CONCLUSIONS: In conclusion, a single dose of repaglinide amplifies insulin secretory burst mass (and basal secretion) with no change in burst frequency. The possible importance of these mechanisms in the treatment of type 2 diabetes characterized by disrupted pulsatile insulin secretion remains to be clarified.

Adult↗
PubMed2000

Lamotrigine add-on for drug-resistant partial epilepsy.

BACKGROUND: Epilepsy is a common neurological disorder, affecting almost 0.5 to 1% of the population. Nearly 30% of patients with epilepsy are refractory to currently available drugs. Lamotrigine is one of the newer antiepileptic drugs and is the topic of this review. OBJECTIVES: To examine the effects of lamotrigine on seizures, side effects, cognition and quality of life, when used as an add-on treatment for patients with drug-resistant partial epilepsy. SEARCH STRATEGY: We searched the Cochrane Epilepsy Group trials register, the Cochrane Controlled Trials Register (Cochrane Library Issue 1, 2000), MEDLINE (January 1966 to December 1999) and reference lists of articles. We also contacted the manufacturers of lamotrigine (Glaxo-Wellcome). SELECTION CRITERIA: Randomized placebo controlled trials, of patients with drug-resistant partial epilepsy of any age, in which an adequate method of concealment of randomization was used. The studies may be double, single or unblinded. For crossover studies, the first treatment period was treated as a parallel trial. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed the trials for inclusion and extracted data. Primary analyses were by intention to treat. Outcomes included 50% or greater reduction in seizure frequency, treatment withdrawal (any reason), side effects, effects on cognition, and quality of life. MAIN RESULTS: We found three parallel add-on studies and eight cross-over studies, which included 1243 patients (199 children and 1044 adults). The overall Peto's Odds Ratio (OR) and 95% confidence intervals (CIs) across all studies for 50% or greater reduction in seizure frequency was 2.71 (1.87, 3.91) indicating that lamotrigine is significantly more effective than placebo in reducing seizure frequency. The overall OR (95%CI) for treatment withdrawal (for any reason) is 1.12 (0.78, 1. 61). The 99% CIs for ataxia, dizziness, nausea, and diplopia do not include unity, indicating that they are significantly associated with lamotrigine. The limited data available preclude any conclusions about effects on cognition and quality of life, though there may be minor benefits in affect balance (happiness) and mastery. REVIEWER'S CONCLUSIONS: Lamotrigine add-on therapy is effective in reducing the seizure frequency, in patients with drug-resistant partial epilepsy. Further trials are needed to assess the long term effects of lamotrigine, and to compare it with other add-on drugs.

Anticonvulsants↗
PubMed1997

The influence of antagonist muscle control strategies on the isometric frequency response of the cat's ankle joint.

This study investigated the effect of various strategies to control the interaction between agonist and antagonist muscles on the frequency response of the isometric cat ankle joint actuated by the tibialis anterior (TA) and soleus (SOL) muscles. Some strategies were based on the physiologic need for increasing joint stability during forceful contractions; with these strategies, the proportional rate of physiologic antagonist activity was termed antagonist gain. Other strategies were based on the electrical stimulation literature, which advocates co-contraction at low force levels. The range of crossover of antagonist activity to the agonist's domain was termed overlap. Strategies consisting of 0%, 10%, and 20% antagonist gain were combined with 0%, 50%, and 100% overlap for a total of nine strategies. These were applied to the TA and SOL using sinusoidal input signals varying in frequency from 0.4 to 6 Hz. Gain and phase Bode plots were constructed through the use of the fast Fourier transforms (FFT's); and analysis of variance determined the significance of differences in gain and phase across frequencies. Best-fit models consisting of four poles and two zeroes were used to fit the experimental data and compared against an analytical model of muscles acting independently across the joint. Harmonic distortion was calculated to evaluate signal quality. It was found that changing the overlap and the antagonist gain produces significant changes in the dynamic response of the two-muscle joint system. The analytical approach to modeling such a system tends to consistently overestimate gain. It is suggested that signal quality is optimal when a moderate amount of antagonist gain (10%) is engaged, with overlap of 50% to smooth transitions between opposing movements. It is expected that this type of strategy will achieve optimum signal quality while preserving the long-term integrity of the joint.

Analysis of Variance↗
PubMed2003

Drugs for preventing migraine headaches in children.

BACKGROUND: It has been estimated that about ten per cent of children between six and 20 years of age suffer from migraine. It is estimated that children with migraine lose one and a half weeks more schooling per year than their peers. Prophylactic drugs can be prescribed when children suffer from frequent or disabling headaches. OBJECTIVES: We aimed to describe and assess the evidence from controlled trials on the efficacy and tolerability of pharmacological agents taken on a regular basis to prevent the occurrence of migraine attacks and/or reduce the intensity of such attacks in children with migraine. SEARCH STRATEGY: The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE were searched from 1966 through 2002. Additional strategies for identifying trials included searching the reference lists of review articles and included studies and searching books related to headache. SELECTION CRITERIA: Prospective randomised controlled trials (RCTs) of self- or parent-administered drug treatments in children (under 18 years of age) who had received a diagnosis of migraine were included. DATA COLLECTION AND ANALYSIS: Two investigators extracted, assessed, and coded separately all data for each study, using a form that was designed specifically for the review. Any disagreement was resolved by discussion. Headache frequency standardised over 28 days was used as the primary outcome measure. Headache intensity, headache duration, amount of symptomatic treatment used, and headache indices were used as secondary outcome measures. Data were extracted from both parallel-group and crossover trials. Continuous and dichotomous data were used to calculate standardised mean differences (SMDs) and odds ratios (ORs), respectively. Numbers-needed-to-treat (NNTs) and numbers-needed-to-harm (NNHs) were also calculated. MAIN RESULTS: Thirty-eight studies were selected. Eighteen were excluded. Eleven preventive drugs were compared with placebo in a total of 15 studies. Drug-drug comparisons were made in just six studies. For only four drugs (L-5-hydroxytryptophan [L-5HTP], flunarizine, clonidine, and propranolol) were two or more studies selected. For only six drugs (trazodone, L-5HTP, propranolol, flunarizine, papaverine, and nimodipine) were data reported for effect on frequency. For no individual drug were comparable data reported in more than one study, thus meta-analysis was not possible. Two placebo-controlled studies showed a beneficial effect on the primary outcome measure, headache frequency. They were for the drugs propranolol and flunarizine. The propranolol study reported a dichotomous outcome (proportion of children responding), and it was possible to calculate a number-needed-to-treat to produce a two-thirds reduction in headache frequency (NNT = 1.5, 95%CI 1.15 to 2.1). The flunarizine study produced a SMD of 1.51 (95% confidence interval, -2.21 to -0.82), which was statistically significant in favour of flunarizine (p < 0.001). Nimodipine, timolol, papaverine, pizotifen, trazodone, L-5HTP, clonidine, metoclopramide, and domperidone showed no efficacy in reduction of frequency of attacks. The available studies on cyproheptadine, phenobarbitone, phenytoin, amitriptyline, carbamazepine, metoprolol, and piracetam were excluded for various reasons. REVIEWER'S CONCLUSIONS: Only one study each for propranolol and flunarizine were identified showing efficacy of these drugs as prophylactics of paediatric migraine. Nimodipine, timolol, papaverine, pizotifen, trazodone, L-5HTP, clonidine, metoclopramide, and domperidone showed no efficacy in reduction of frequency of attacks. Available studies on other commonly used drugs failed to meet our inclusion criteria. The quality of evidence available for the use of drug prophylaxis in paediatric migraine was poor. Studies were generally small, with no planning of sample size, so that for many drugs, despite the negative findings of this review, we do not have conclusive evidence of 'no effect'. There is a clear and urgent need for methodologically sound RCTs for the use of pings of this review, we do not have conclusive evidence of 'no effect'. There is a clear and urgent need for methodologically sound RCTs for the use of prophylactic drugs in paediatric migraine, starting with propranolol. These studies need to be adequately powered to investigate meaningful reductions in pain and suffering from a patient's perspective.

Adolescent↗