PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “crossover”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 379 records · Page 21Linked to original sources

Luteal phase sertraline treatment for premenstrual dysphoric disorder. Results of a double-blind, placebo-controlled, crossover study.

OBJECTIVE: To test the efficacy of late-luteal phase dosing of sertraline hydrochloride in women with moderate-to-severe premenstrual dysphoric disorder. This highly prevalent disorder often causes significant psychosocial impairment. DESIGN: Double-blind, crossover trial of each 2-menstrual cycle of baseline, sertraline treatment, and placebo. Randomization to sertraline treatment vs placebo occurred after a 2-cycle, drug-free period. SETTING: A large outpatient multispecialty clinic in central Texas. PATIENTS: Fifty-seven women aged 19 to 49 years with a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnosis of premenstrual dysphoric disorder. INTERVENTIONS: Late-luteal phase treatment with sertraline hydrochloride in daily doses of 50 mg (cycle 1) followed by 100 mg (cycle 2) vs placebo. MAIN OUTCOME MEASURES: The 22-item calendar of premenstrual experiences was completed daily and constituted the primary outcome measure, consisting of a total score and behavioral and physical factor scores. RESULTS: A repeated-measures analysis of variance for crossover designs found a significant beneficial effect from sertraline treatment in improving the calendar of premenstrual experiences total (P < .01), behavioral factor (P < .01), and physical factor (P < .04) scores. Most women improved when taking sertraline, 50 mg, although a dose increase to 100 mg yielded further improvement in approximately 25% of women. Use of sertraline was extremely well tolerated; the only adverse event reported by 10% or more of women was insomnia in 8 (14%) of them. CONCLUSIONS: Luteal phase treatment with sertraline was a safe and effective treatment for moderate-to-severe premenstrual dysphoric disorder. Further controlled studies are needed to confirm the results of this preliminary study.

Adult↗

Acoustic reflex crossover artifacts in infants and young children.

Crossover artifacts occur when the probe microphone of an impedance instrument directly responds to vibratory-acoustic energy that crosses the skull from the stimulus transducer on the contralateral ear. The resulting meter deflections are subjectively similar to and may be interpreted as actual acoustic reflexes (ARs) by unsuspecting examiners. In this study, infants and young children aged 10 days to 6 years 9 months were fit with earplugs to eliminate the AR and were examined for artifact incidence and threshold. Results indicate a high rate of occurrence of the crossover artifact in the youngest subjects, when probe tones of 220 and 660 Hz were used with stimuli of 500 and 1,000 Hz. Artifact thresholds were found as low as at a 92-dB hearing level, and an inverse relationship was shown between age and artifact incidence and threshold.

Acoustic Impedance Tests↗

Randomized, controlled, crossover trial of methylphenidate in pervasive developmental disorders with hyperactivity.

CONTEXT: Hyperactivity and inattention are common symptoms in children with autistic disorder and related pervasive developmental disorders, but studies of stimulants in these conditions have been inconclusive. OBJECTIVES: To determine the efficacy and safety of methylphenidate hydrochloride in children with pervasive developmental disorders and hyperactivity. DESIGN: Double-blind, placebo-controlled, crossover trial followed by open-label continuation. SETTING: Five academic outpatient clinics. PARTICIPANTS: Seventy-two drug-free children, aged 5 to 14 years, with pervasive developmental disorders accompanied by moderate to severe hyperactivity. INTERVENTIONS: Prior to randomization, subjects entered a 1-week test-dose phase in which each subject received placebo for 1 day followed by increasing doses of methylphenidate (low, medium, and high doses) that were each given for 2 days. The low, medium, and high doses of methylphenidate hydrochloride were based on weight, and they ranged from 7.5 mg/d to 50.0 mg/d in divided doses. Subjects who tolerated the test dose (n = 66) were assigned to receive placebo for 1 week and then 3 methylphenidate doses in random order during a double-blind, crossover phase. Children responding to methylphenidate then entered 8 weeks of open-label treatment at the individually determined best dose. MAIN OUTCOME MEASURES: The primary outcome measure was the teacher-rated hyperactivity subscale of the Aberrant Behavior Checklist. Response was defined as "much improved" or "very much improved" on the Clinical Global Impressions Improvement item coupled with considerable reductions in the parent-rated and/or teacher-rated Aberrant Behavior Checklist hyperactivity subscale score. RESULTS: Methylphenidate was superior to placebo on the primary outcome measure, with effect sizes ranging from 0.20 to 0.54 depending on dose and rater. Thirty-five (49%) of 72 enrolled subjects were classified as methylphenidate responders. Adverse effects led to the discontinuation of study medication in 13 (18%) of 72 subjects. CONCLUSIONS: Methylphenidate was often efficacious in treating hyperactivity associated with pervasive developmental disorders, but the magnitude of response was less than that seen in typically developing children with attention-deficit/hyperactivity disorder. Adverse effects were more frequent.

Adolescent↗

Crossover femorofemoral grafts followed up five years or more. An analysis.

Crossover femorofemoral grafts continue to provide satisfactory long-term patency with low morbidity and mortality in the treatment of unilateral atherosclerotic iliac artery occlusion. In our series of patients, early failures were primarily a result of the inability to provide adequate runoff for the graft, and late failures were due to progressive atherosclerotic involvement of runoff vessels. Clear-cut progression of the atherosclerotic process in the donor iliac artery segment has not been observed in this series. In fact, there is evidence that suggests that this process may have been retarded when compared with other types of reconstructive procedures. There is a noticeably late mortality (33%) due to other disease processes and associated cardiovascular disorders. These facts continue to support the application of crossover femorofemoral grafts in the surgical treatment of unilateral atherosclerotic illiac artery occlusions.

Adult↗

Crossover femorofemoropopliteal sequential bypass for combined ipsilateral iliac and femoropopliteal occlusive disease.

We evaluated the effectiveness of crossover femorofemoropopliteal sequential bypass in 13 patients with combined ipsilateral iliac and femoropopliteal disease. Of them, eight underwent bypass grafting for limb salvage, and five, for disabling claudication. Four of the patients with claudication had relief of symptoms and significant increases in treadmill walking time. The cumulative limb salvage rate in the patients operated on for limb salvage was 88%. At 42 months, the cumulative patency rate for the femorofemoral portion of the graft was 91%, and for the distal segment, 63%. Mean ankle-brachial indices increased from 0.37 +/- 0.12 preoperatively to 0.76 +/- 0.16 postoperatively in the recipient limb. Early experience suggests that crossover sequential femorofemoropopliteal bypass grafts are effective in achieving limb salvage and relief of claudication, especially in patients with relative contraindications to major intra-abdominal surgery.

Aged↗

The antiosteoporotic efficacy of intravenous pamidronate in men with prostate carcinoma receiving combined androgen blockade: a double blind, randomized, placebo-controlled crossover study.

BACKGROUND: Prostate carcinoma therapy with combined androgen blockade may result in high bone-turnover with significant bone loss. This study was undertaken to evaluate the antiosteoporotic efficacy of intravenous pamidronate in a double blind, randomized, placebo-controlled, crossover study. METHODS: Twenty-one consecutive men with metastatic prostate carcinoma who were receiving combined androgen blockade with a long-acting gonadotropin-releasing hormone agonist (gosarelin acetate) and an androgen antagonist (flutamide or bicalutamide) were evaluated at baseline and at 6 and 12 months after therapy. They were randomly assigned to receive a single intravenous infusion of 500 mL of normal saline solution diluted with either pamidronate (90 mg) or placebo at baseline and with a crossover at 6 months. Lumbar-spine bone-mineral densities (BMDs) were measured by spinal quantitative computed tomography (QCT), femoral neck BMDs were measured by dual-energy X-ray absorptiometry (DXA), and markers of bone turnover were measured by noninvasive methods. Data on 10 men with localized prostate carcinoma who were treated with radiotherapy alone, over the same period, was collected for comparison studies. RESULTS: The mean age of the men was 75.1 years +/- 1.6 years. One man withdrew from the study because of deteriorating health, and two died from metastatic disease within the first 6 months. Combined androgen blockade normalized serum prostate-specific antigen activities (from an initial mean value of 86.2 ng/mL +/- 10.1 ng/mL) and maintained serum free testosterone concentrations in the hypogonadal range (< 2.2 pmol/L) in all men throughout the study. Treatment with pamidronate resulted in a 7.8% +/- 1.5% increase in mean lumbar spine QCT from 79.4 mg/cm(3) (95% confidence interval [CI], 64-94 mg/cm(3)) to 85.6 mg/cm(3) (95% CI, 70-101 mg/cm(3)) (P = 0.0005) and a 2% +/- 0.9% increase in mean total femoral neck DXA from 0.98 g/cm(2) (95% CI, 0.90 -1.05 g/cm(2)) to 1.0 mg/cm(2) (95% CI, 0.91-1.08 g/cm(2)) (P = 0.02). Conversely, treatment with placebo, resulted in a 5.7% +/- 1.6% decrease in mean lumbar spine QCT and a 2.3% +/- 0.7% decrease in mean total femoral neck DXA (P = 0.0001 and P = 0.0007 for the comparison of percentage change between the pamidronate and placebo treatments). After pamidronate therapy, serum bone Gla-protein concentrations decreased by 16.8% +/- 5.9%, and urinary deoxypyridinoline excretion rates decreased by 18.5% +/- 12.8% (P < 0.01 respectively for the comparison between pamidronate and placebo treatment). CONCLUSIONS: This study demonstrated that a single intravenous infusion of pamidronate (90 mg) significantly reduced the high bone turnover and bone loss (for at least 6 mos) in men with prostate carcinoma who had been rendered hypogonadal with combined androgen blockade therapy.

Aged↗

Photomagnetic properties in a series of spin crossover compounds

The spin crossover (SC) compounds [Fe(PM-AzA)2(NCX)2] and [Fe(PM-FIA)2(NCX)2] (with PM-AzA = N-2'-pyridylmethylene-4-(phe-nylazo)aniline, PM-FIA = N-2'-pyridylmethylene-4-(2-amino)fluorene, and X = S, Se) have been prepared. The SC regimes have been deduced from variable-temperature magnetic susceptibility data. The enthalpy and entropy changes associated with the SC have been evaluated from DSC measurements. A cooperativity factor, C, has been defined, and its values for the different compounds have been deduced from the spin crossover curves. At 10 K, the light-induced excited spin state trapping (LIESST) effect has been observed within the cavity of the SQUID magnetometer. The critical temperatures Tc(LIESST) have been determined for [Fe(PM-AzA)2(NCS)2] and [Fe(PM-F1A)2(NCX)2], and the role of cooperativity has been analyzed. A linear correlation has been found between the Tc(LIESST) and C values. The kinetics of HS-->LS relaxation have been investigated; a thermally activated mechanism at elevated temperatures and a nearly temperature independent relaxation behavior at low temperatures have been found. Finally, the magnetic behavior recorded under light irradiation in the warming and cooling modes has revealed the occurrence of the light-induced thermal hysteresis (LITH) effect.

Journal Article↗

Effects of a 30 kV/m, 60 Hz electric field on the social behavior of baboons: a crossover experiment.

Using a crossover experimental design, we evaluated our earlier findings that exposure to a 30 kV/m, 60 Hz electric field for 12 hours per day, 7 days per week for 6 weeks produced significant changes in the performance rates of social behaviors among young adult male baboons. In the crossover experiment, the former control group was exposed to a 30 kV/m, 60 Hz electric field for 3 weeks. Only an extremely small, incidental magnetic field was generated by the exposure apparatus. We found that electric-field exposure again produced increases in the performance rates that index Passive Affinity, Tension, and Stereotypy. These findings, combined with results from our other electric-field experiments, indicate that exposure to strong electric fields, in the absence of associated magnetic fields, consistently produces effects that are expressed as increases in rates of performance of social behaviors in young adult male baboons.

Animals↗

Behavioral testing of antidepressant compounds: an analysis of crossover design for correlated binary data.

The differential reinforcement of low-rate 72 seconds schedule (DRL-72) is a standard behavioral test procedure for screening potential antidepressant compounds. The protocol for the DRL-72 experiment, proposed by Evenden et al. (1993), consists of using a crossover design for the experiment and one-way ANOVA for the statistical analysis. In this paper we discuss the choice of several crossover designs for the DRL-72 experiment and propose to estimate the treatment effects using either generalized linear mixed models (GLMM) or generalized estimating equation (GEE) models for clustered binary data.

Algorithms↗

Critical appraisal of femorofemoral crossover grafts.

BACKGROUND: The aim of this study was to determine how often femorofemoral crossover grafting for critical ischaemia or intermittent claudication gives an ideal result. An ideal result is an uncomplicated operation with primary wound healing, relief of ischaemic symptoms without recurrence and no need for further intervention. METHODS: All patients undergoing primary femorofemoral crossover grafting between January 1988 and December 2003 were studied. RESULTS: Some 144 operations were analysed; 51 patients had critical ischaemia and 93 claudication. There was one postoperative death (0.7 per cent). Complications occurred within 30 days in 32 patients (22.2 per cent), including graft occlusion in three (2.1 per cent); six patients (4.2 per cent) required early reoperation. Primary patency for patients with critical ischaemia was 88, 82 and 74 per cent at 1, 3 and 5 years respectively. Respective figures for those who presented with claudication were 93, 92 and 90 per cent (P = 0.034). Late symptoms included graft occlusion (20 patients), disease progression (25), ongoing ulceration (six), graft infection (nine), false aneurysm formation (two) and late donor-site stenosis (two). CONCLUSION: When obtaining informed consent, simply describing patency and limb salvage rates does not provide an accurate picture of the outcome of femorofemoral grafting.

Aged↗

A range of spin-crossover temperature T1/2>300 K results from out-of-sphere anion exchange in a series of ferrous materials based on the 4-(4-imidazolylmethyl)-2-(2-imidazolylmethyl)imidazole (trim) ligand, [Fe(trim)2]X2 (X=F, Cl, Br, I): comparison of experimental results with those derived from density functional theory calculations.

The synthesis and characterization of [FeII(trim)2]Cl2 (2), [FeII(trim)2]Br2MeOH (3), and [FeII(trim)2]I2MeOH (4), including the X-ray crystal structure determinations of 2 (50 and 293 K) and 4 (293 K), have been performed and their properties have been examined. In agreement with the magnetic susceptibility results, the Mössbauer data show the presence of high-spin (HS) to low-spin (LS) crossover with a range of T1/2 larger than 300 K (from approximately 20 K for [FeII(trim)2]F2 (1) to approximately 380 K for 4). All complexes in this series include the same [Fe(trim)2]2+ complex cation: the ligand field comprises a constant contribution from the trim ligands and a variable one originating from the out-of-sphere anions, which is transmitted to the metal center by the connecting imidazole rings and hydrogen bonds. The impressive variation in the intrinsic characteristics of the spin-crossover (SCO) phenomenon in this series is then interpreted as an inductive effect of the anions transmitted to the nitrogen donors through the hydrogen bonds. Based on this qualitative analysis, an increased inductive effect of the out-of-sphere anion corresponds to a decreased SCO temperature T1/2, in agreement with the experimental results. Electronic structure calculations with periodic boundary conditions have been performed that show the importance of intermolecular effects in tuning the ligand field, and thus in determining the transition temperature. Starting with the geometries obtained from the X-ray studies, the [FeII(trim)2]X2 complex molecules 1-4 have been investigated both for the single molecules and the crystal lattices with the local density approximation of density functional theory. The bulk geometries of the complex cations deduced from the X-ray studies and those calculated are in fair agreement for both approaches. However, the trend observed for the transition temperatures of 1-4 disagrees with the trend for the spin-state splittings ES (difference EHS-ELS between the energy of the HS and LS isomers) calculated for the isolated molecules, whereas it agrees with the trend for ES calculated with periodic boundary conditions. The latter calculations predict the strongest stabilization of the HS state for the fluoride complex, which actually is essentially HS above T=50 K, while the most pronounced stabilization of the LS state is predicted for 4, in line with the experimental results.

Journal Article↗

Photoexcitation and relaxation dynamics of catecholato-iron(III) spin-crossover complexes.

The photophysical properties of the ferric catecholate spin-crossover compounds [(TPA)Fe(R-Cat)]X (TPA=tris(2-pyridylmethyl)amine; X=PF(6) (-), BPh(4) (-); R-Cat=catecholate dianion substituted by R=NO(2), Cl, or H) are investigated in the solid state. The catecholate-to-iron(III) charge-transfer bands are sensitive both to the spin state of the metal ion and the charge-transfer interactions associated with the different catecholate substituents. Vibronic progressions are identified in the near-infrared (NIR) absorption of the low-spin species. Evidence for a low-temperature photoexcitation process is provided. The relaxation dynamics between 10 and 100 K indicate a pure tunneling process below approximately 40 K, and a thermally activated region at higher temperatures. The relaxation rate constants in the tunneling regime at low temperature, k(HL)(T-->0), vary in the range from 0.58 to 8.84 s(-1). These values are in qualitative agreement with the inverse energy-gap law and with structural parameters. A comparison with ferrous spin-crossover complexes shows that the high-spin to low-spin relaxation is generally faster for ferric complexes, owing to the smaller bond length changes for the latter. However, in the present case the corresponding rate constants are smaller than expected based on the single configurational coordinate model. This is attributed to the combined influence of the electronic configuration and the molecular geometry.

Journal Article↗

Locus ordering based on crossover information in family haplotypes: application of a "minimum break" algorithm.

A "minimum break" method, previously applied to radiation hybrid data, is applied to the Genetic Analysis Workshop 12 simulated family data to assess the method's feasibility for ordering dense markers that have been typed in a set of pedigrees of three or more generations. Ordering is based on minimizing the total number of crossovers ("breaks") in a set of haplotypes where allele origin can be assigned to each specific haplotype, but locus order is unknown. It is shown that, for average locus spacing of about 2 cM and a set of 300 to 600 haplotypes, locus ordering can be reliably determined for sets of at least 50 loci. However, in the absence of crossovers between some pairs (sets) of loci, no unique order can be identified and sets of orders that are equally likely will be recovered. The method presented can be used to obtain reasonable sets of ordered loci that can then be used by other methods to refine the statistical confidence of the locus order.

Algorithms↗

A randomized, controlled crossover trial of ondansetron in patients with primary biliary cirrhosis and fatigue.

Fatigue is common in primary biliary cirrhosis (PBC). Altered central serotonergic neurotransmission may be involved in its pathogenesis. This multicenter, randomized, double-blind, placebo-controlled, crossover trial evaluated the efficacy of ondansetron, a selective 5-HT3 receptor subtype antagonist, for treating fatigue in PBC. A crossover design was chosen, allowing subjects to serve as their own controls-appropriate to evaluate fatigue, a subjective symptom. Sixty patients with clinically stable PBC, a Fatigue Severity Score (FSS) > 4, and no other identifiable cause for fatigue were enrolled. Subjects were randomized to receive ondansetron (4 mg) or placebo orally 3 times daily for 4 weeks (period 1). Subjects then crossed over, after a minimum 1-week washout period, for a further 4 weeks of ondansetron or placebo (period 2). Fatigue was measured at the beginning and end of each period by using the FSS and Fatigue Impact Scale (FIS). Six patients withdrew; the remaining 54 subjects had a mean baseline FSS of 5.55 (+/-0.1). Response to study medication in period 1 versus period 2 was not uniform; thus, it was necessary to analyze the trial periods separately. In period 1, there was no significant additional fatigue reduction on ondansetron over placebo. During period 2, FSS and FIS decreased significantly on ondansetron versus placebo (P = .001). However, period 2 results were invalidated because drug side effects unblinded subjects (constipation affected 63.0% of patients taking ondansetron, versus 13.3% on placebo). In conclusion, ondansetron administration did not confer clinically significant fatigue reduction when compared with placebo in our study population.

Constipation↗

Ankylosing spondylitis: open long-term and double-blind crossover studies with naproxen.

Participation in open and double-blind crossover studies in rheumatoid arthritis confirmed that naproxen improved pain and stiffness. This observation suggested that naproxen might be effective in ankylosing spondylitis. The initial trial was open, but at six months, a double-blind crossover "placebo pulse" was superimposed on the open trial. Thirty-six patients entered the trial taking a daily dose of 500 mg naproxen. At the end of the first month, 35 assessed naproxen as being equally effective to, or better than, previous therapy. The first ten patients to complete six months on naproxen took part in a placebo pulse study comprising two consecutive four-week periods, in one of which each patient took 500 mg naproxen, in the other, identical placebo capsules, the order being randomized. Eight patients correctly identified the placebo capsules (P=0.02). During the 16 months of trial, six patients have withdrawn, two being in remission and four for lack of efficacy. The remaining 30 patients have completed six months and 22 have completed at least 12 months on naproxen. At the end of six months pain was less (P=0.02), morning stiffness had decreased (P less than 0.01), and immobility stiffness had improved (P less than 0.01). These patients are impressed by the improvement in pain and stiffness and have little disability. All continue full-time employment and have been able to increase their leisure activities without discomfort. No persistent side effects were observed, and naproxen appears to be a useful drug in the treatment of anklyosing spondylitis.

Anti-Inflammatory Agents↗

Double-blind multiple-dose crossover study of the antiemetic effect of intramuscular levonantradol compared to prochlorperazine.

Twenty cancer patients who received chemotherapy were entered into a double-blind crossover design antiemetic study comparing 1 mg levonantradol, an investigational synthetic cannabinoid, to 10 mg prochlorperazine. Sixteen patients completed the crossover. For each antiemetic course, four doses of each study medication were given intramuscularly 2 hours before chemotherapy and then 2, 6, and 10 hours after chemotherapy administration. There were no statistical differences in patients' responses to levonantradol and prochlorperazine. The frequency of side effects was greater with levonantradol than with prochlorperazine. The most common side effect of levonantradol were somnolence, dry mouth, dizziness, tachycardia, postural hypotension, and blurred vision, while those for prochlorperazine were somnolence, dry mouth, and tachycardia.

Adolescent↗

A simple method for the estimation of interaction bias in crossover studies.

The crossover trial is considered the most powerful means of determining the efficacy of new drugs. However this study design is frequently invalidated by treatment-by-period interaction. If, for example, the effect of the first treatment period carries on into the next one, then it influences the response to the latter period (carryover effect). A second problem is that there are no reliable statistical methods to test for this potential bias. This article takes issue with these problems and gives an alternative method for the detection of interaction simply by looking at the data. In a crossover without interaction the second period should be a true reflection of the first. If, however, the data of a treatment are better in the second period than in the first, a carryover effect is probable. If worse, a rebound phenomenon or a negative carryover effect is likely. If both treatments are better or worse, a time effect or some other external influence might be present. The authors illustrate this simple method by a summary of a few selected trials that have been published recently. This method enables not only the detection of interaction but also the differentiation between different types of interactions. Therefore, investigators are advised to use it in order to make sure that there are no unexpected problems.

Bias↗

Treatment of men with idiopathic oligozoospermic infertility using the aromatase inhibitor, testolactone. Results of a double-blinded, randomized, placebo-controlled trial with crossover.

The hypothesis that increased estradiol production may be the cause of impaired spermatogenesis in infertile men with idiopathic oligozoospermia was tested by administering the aromatase inhibitor, testolactone, and by assessing its effects on sperm output and fertility. Our study was a randomized, placebo-controlled double-blind crossover trial. Subjects (n = 25) with infertility due to unexplained oligozoospermia were given testolactone (2 g/day) or placebo for 8 months followed by crossover to the other treatment for an additional 8 months. Total estradiol and testosterone levels during testolactone exposure did not change from basal and placebo values. However, sex hormone-binding globulin binding capacity consistently decreased (30%, p less than 0.01) and free testosterone levels increased (36%, p less than 0.01). Free estradiol values increased but not significantly. Additionally, LH and FSH serum levels increased by 15% and 20%, respectively (p less than 0.05), and 17 alpha-hydroxyprogesterone values increased by 90% (p less than 0.05) during drug administration. Sperm output and semen quality remained unchanged during either testolactone or placebo treatment, and no pregnancies occurred during the 16-month study. These data suggest that chronic administration of testolactone at this dose fails to maintain aromatase inhibition despite depression of 17,20-desmolase activity with elevated 17 alpha-hydroxyprogesterone and depressed SHBG binding capacity with elevation of free testosterone. Testolactone is not efficacious in the treatment of idiopathic oligozoospermic infertility.

Adult↗