Conclusive Results (conclusive + result)

Distribution by Scientific Domains


Selected Abstracts


Microwave-Assisted Hydrothermal Synthesis of Structurally and Morphologically Controlled Sodium Niobates by Using Niobic Acid as a Precursor

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2008
Amauri J. Paula
Abstract There are many advantages to using a microwave as a source of heat in hydrothermal reactions. Because it is a quick and homogeneous way to crystallize ceramic powders, it was used in this work for the production of antiferroelectric sodium niobate (NaNbO3) in a cubic-like form and its intermediary phase, disodium diniobate hydrate (Na2Nb2O6.H2O), with a fiber morphology. The syntheses were carried out by treating niobic acid (Nb2O5·nH2O) with NaOH. By changing the reaction time and the concentration of the reactants, particles with different structures and different morphologies could be obtained. The structural evolution of the products of this reaction was elucidated on the basis of the arrangement of the NbO6 octahedral units. Conclusive results were obtained with morphological and structural characterizations through XRD, TEM, MEV, and NMR and Raman spectroscopy. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


Residual risk for acute stroke in patients with type 2 diabetes and hypertension in primary care: Skaraborg Hypertension and Diabetes Project

DIABETES OBESITY & METABOLISM, Issue 5 2006
K. Junga
Aim:, The aim of this study was to investigate the risk of acute stroke in subgroups of patients treated for hypertension and type 2 diabetes in primary care. Methods:, Patients with hypertension only (n = 695), type 2 diabetes only (n = 181) or both (n = 240), who consecutively attended an annual control in primary care in Skara, Sweden during 1992,1993, were evaluated for cardiovascular disease risk factors and enrolled in this study. Subjects with neither hypertension nor type 2 diabetes (n = 824) who participated in a population survey in the same community served as controls. Possible events of acute stroke through 2002 were validated using hospital records and death certificates. Results:, During a mean follow-up time of 8.4 years, 190 first events of acute stroke, fatal or non-fatal, were ascertained. Risk factor levels were generally higher in all patient categories than in controls. Stroke risk was significantly increased in all male patients: hazard ratio 4.2 (95% CI 2.1,8.4) in patients with both conditions, 3.3 (1.5,7.0) in those with type 2 diabetes alone and 2.8 (1.5,5.3) in those with hypertension alone (adjusted for age, total cholesterol, current smoking, BMI and physical activity). Corresponding findings in women were 2.9 (1.5,5.8) in patients with type 2 diabetes only and 2.4 (1.2,4.7) in those with both conditions. However, in women with hypertension only, a significant risk was seen first when subjects were truncated at 85 years of age. There were too few fatal stroke events for conclusive results on stroke mortality. Conclusions:, A considerable risk of acute stroke remains in patients with type 2 diabetes and hypertension. Strategies for stricter multiple risk factor interventions should be implemented in primary care. [source]


Navigating toward Fetal and Maternal Health: The Challenge of Treating Epilepsy in Pregnancy

EPILEPSIA, Issue 10 2004
Torbjörn Tomson
Summary:, A rational approach to the treatment of women of childbearing potential with epilepsy has been hampered by the lack of conclusive data on the comparative teratogenic potential of different antiepileptic drugs (AEDs). Although, several cohort studies on birth defects associated with AED use during pregnancy have been published, these have generally failed to demonstrate differences in malformation rates between AEDs, probably mainly due to insufficient power. In particular, pregnancies with new generation AEDs have been too few. In recent years, pregnancy registries have been introduced to overcome this problem,EURAP (an international collaboration), the North American, and the U.K. AED and pregnancy registries are observational studies that prospectively assess pregnancy outcome after AED exposure using slightly different methods. Each has enlisted 3,5,000 pregnancies in women with epilepsy, and the North American and the U.K. have released preliminary observations. Thus the U.K. registry reported a higher malformation rate with valproate, 5.9% (4.3,8.2%; 95% CI), than with carbamazepine, 2.3% (1.4,3.7%), and lamotrigine, 2.1% (1.0,4.0%). Most of the more recent cohort studies have also identified a nonsignificant trend toward a higher teratogenicity with valproate. These signals need to be interpreted with some caution since none of the studies to date have fully assessed the impact of possible confounders, such as type of epilepsy, family history of birth defects, etc. However, with increasing number of pregnancies it should be possible in the near future for the pregnancy registries to take such confounding factors into account and thus make more reliable assessments of the causal relationship between exposure to specific AEDs and teratogenic risks. While awaiting more conclusive results, it appears reasonable to be cautious in prescribing valproate to women considering to become pregnant if other suitable treatment alternatives, and with less teratogenic potential, are available. Any attempt to change treatment should, however, be accomplished well before conception. The importance of maintained seizure control must also be kept in mind, and the woman who needs valproate to control her seizures should not be discouraged from pregnancy, provided that counseling at the best of available knowledge is given. [source]


Investigation of 17 candidate genes for personality traits confirms effects of the HTR2A gene on novelty seeking

GENES, BRAIN AND BEHAVIOR, Issue 4 2009
A. Heck
Genes involved in serotonergic and dopaminergic neurotransmission have been hypothesized to affect different aspects of personality, but findings from genetic association studies did not provide conclusive results so far. In previous studies, however, only one or a few polymorphisms within single genes were investigated neglecting the possibility that the genetic associations might be more complex comprising several genes or gene regions. To overcome this limitation, we performed an extended genetic association study analyzing 17 serotonergic (SLC6A4, HTR1A, HTR1B, HTR2A, HTR2C, HTR3A, HTR6, MAOA, TPH1, TPH2) and dopaminergic genes (SLC6A3, DRD2, DRD3, DRD4, COMT, MAOA, TH, DBH), which have been previously reported to be implicated with personality traits. One hundred and ninety-five single nucleotide polymorphisms (SNPs) within these genes were genotyped with the Illumina BeadChip technology (HumanHap300, Human-1) in a sample of 366 mentally healthy Caucasians. Additionally, we tried to replicate our results in an independent sample of further 335 Caucasians. Personality traits in both samples were assessed with the German version of Cloninger's Tridimensional Personality Questionnaire. From 30 SNPs showing associations at a nominal level of significance, two intronic SNPs, rs2770296 and rs927544, both located in the HTR2A gene, withstood correction for multiple testing. These SNPs were associated with the personality trait novelty seeking. The effect of rs927544 could be replicated for the novelty seeking subscale extravagance, and the same SNP was also associated with extravagance inthe combined samples. Our results show that HTR2A polymorphisms modulate facets of novelty seeking behaviour in healthy adults suggesting that serotonergic neurotransmission is involved in this phenotype. [source]


Laboratory environments are not conducive for allopatric speciation

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2002
A.-B. Florin
We review published records of laboratory experiments on peripatric and vicariance allopatric speciation to address the following three questions: (1) What was the true effect size of reproductive isolation? (2) Was the reproductive isolation persistent? (3) What influenced the development of isolation? Contrary to popular belief, laboratory evidence for allopatric speciation is quite weak. Assortative mating was only found among derived populations in vicariance experiments. Reproductive isolation against control populations was only intermittent, so there is reason to doubt if some cases showing significant reproductive isolation really should be attributed to speciation. The method of testing was at least as important as the speciation model. Experimental populations tested against each other were the most likely to demonstrate reproductive isolation. This study suggests that allopatric speciation experiments are more likely to yield conclusive results under divergent selection than under drift, and points to the benefits of large populations and many generations. [source]


A "cure" for Parkinson's disease: Can neuroprotection be proven with current trial designs?

MOVEMENT DISORDERS, Issue 5 2004
Carl E. Clarke BSc
Abstract Current medical and surgical therapies for Parkinson's disease provide symptomatic control of motor impairments rather than slowing or halting the progression of the disease. Previous clinical trials examining drugs such as dopamine agonists and selegiline for neuroprotective effects used "surrogate" outcomes, including clinical measures (rating scales, time to require levodopa), neuroimaging techniques (,-CIT single photon emission computed tomography; fluorodopa positron emission tomography), and mortality tracking. These studies failed to provide conclusive results because of design faults such as failing to control for symptomatic effects, small sample size, and not accounting for the possible effects of drugs on radionuclide tracer handling. Lessons must be learned from these failed neuroprotection trials. This review summarises the problems with previous neuroprotection studies and makes recommendations for future trial design. It is concluded that the primary outcome of explanatory trials should continue to be clinical measures such as the Unified Parkinson's Disease Rating Scale (UPDRS). It should be assumed that all agents have a symptomatic effect, which necessitates evaluation after a prolonged drug washout period. To achieve the evaluation after a prolonged drug washout period more effectively, trials must be performed in early disease and over a short period (6,12 months) so that symptomatic therapy is not required. To achieve adequate statistical power, these trials will need to include thousands of patients. Radionuclide imaging can only be used in such trials after considerable methodological work has been performed to establish its validity and reliability. To be affordable, such large explanatory trials need more streamlined designs with fewer hospital visits, fewer outcome measures, and rationalised safety monitoring. The clinical effectiveness of promising compounds from explanatory trials will need to be established in large long-term pragmatic trials using outcome measures such as quality of life, cost-effectiveness, and mortality. Such pragmatic trials could be continuations of the explanatory trials: after the primary outcome of the explanatory study (e.g., UPDRS) has been reported in an interim analysis, the trial could be continued for a further 5 to 10 years to report on quality of life and health economics outcomes. © 2004 Movement Disorder Society [source]


Psychosocial interventions for adolescent cancer patients: a systematic review of the literature

PSYCHO-ONCOLOGY, Issue 7 2009
Diana C. M. Seitz
Abstract Objective: Both cancer diagnosis and the consequent treatment are particularly challenging for adolescent patients. Adjuvant psychological interventions to reduce cancer-related distress are therefore a fundamental part of a multidisciplinary treatment. Assuming that psycho-oncology has to consider developmentally specific aspects, this review summarizes empirical studies of the efficacy and effectiveness of psychosocial interventions for adolescent cancer patients. Methods: Electronic searches were conducted in four databases. Studies were included only if they were exclusively designed for adolescent cancer patients and incorporated a defined outcome measure to evaluate the effects of the implemented intervention. Results: Only four studies fulfilled the inclusion criteria. One of those studies reported a significant improvement compared with a waitlist control group. The relevant gains were found in the overall level of distress, as well as in additional outcome variables such as knowledge of sexual issues, body image and anxiety about psychosexual issues. The remaining studies revealed no significant changes related to psychological distress and psychosocial functioning. Conclusion: Taken together, the findings point out that there is a lack of intervention research in psycho-oncology with adolescents. So far, there is only limited evidence for the effectiveness of psychosocial interventions to improve coping with cancer-associated problems in adolescent patients. Future research needs to be done in this population. In order to establish more conclusive results, larger samples and interventions particularly designed for adolescent patients ought to be studied. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Pitfalls in the design and analysis of paediatric clinical trials: a case of a ,failed' multi-centre study, and potential solutions

ACTA PAEDIATRICA, Issue 2 2009
Johanna H Van Der Lee
Abstract Aim: To increase awareness of possible pitfalls in the design and analysis of a multi-centre randomized clinical trial and to give an overview of alternative study designs and their consequences for power analyses in case of limited availability of trial participants. Methods: Investigation of the assumptions in the power calculation and re-analysis of the original data of a ,failed' trial on the effect of dexamethasone on the duration of mechanical ventilation in young children with respiratory syncytial virus infection. Use of ,boundaries approach' is explored using the data from this trial. A comprehensive overview of the various modern solutions for the design of a subsequent trial in this field is given. Results: Two frequent major deficiencies of trial design and data analysis are reviewed in depth, i.e. too optimistic assumptions for the sample size calculation and failure to adjust for centre effects. Conclusion: Critical review of trial assumptions and if necessary sample size recalculation based on an internal pilot by a data monitoring committee is recommended to maximize the probability of obtaining conclusive results. [source]