Possible Reasons For Inconsistent Results Research Articles

A proposed theoretical framework for retinal biomarkers.

ObjectivePropose a theoretical framework for retinal biomarkers of Alzheimer's disease (AD).BackgroundThe retina and brain share important biological features that are relevant to AD. Developing retinal biomarkers of AD is a strategic priority but as yet none have been validated for clinical use. Part of the reason may be that fundamental inferential assumptions have been overlooked. Failing to recognize these assumptions will disadvantage biomarker discovery and validation, but incorporating them into analyses could facilitate translation.New theoryThe biological assumption that a disease causes analogous effects in the brain and retina can be expressed within a Bayesian network. This allows inferences about abstract theory and individual events, and provides an opportunity to falsify the foundational hypothesis of retina–brain analogy. Graphical representation of the relationships between variables simplifies comparison between studies and facilitates judgements about whether key assumptions are valid given the current state of knowledge.Major challengesThe framework provides a visual approach to retinal biomarkers and may help to rationalize analysis of future studies. It suggests possible reasons for inconsistent results in existing literature on AD biomarkers.Linkage to other theoriesThe framework can be modified to describe alternative theories of retinal biomarker biology, such as retrograde degeneration resulting from brain disease, and can incorporate confounding factors such as co‐existent glaucoma or macular degeneration. Parallels with analogue confirmation theory and surrogate marker validation suggest strengths and weaknesses of the framework that can be anticipated when developing analysis plans.Highlights Retinal biomarkers hold great promise for Alzheimer's disease (AD), but none are currently used clinically.Assumptions about the cause of retinal and brain changes are often overlooked, and this may disadvantage biomarker discovery and validation.We present a new approach to retinal biomarkers that describes cause and effect graphically in a Bayesian network.We show how this allows a more complete assessment of how well a biomarker might reflect the brain, and how data from right and left eyes can be used to rule out poor biomarker candidates.

Impact of Omega-3 Fatty Acid Supplements on Gastrointestinal Cancer Patients after Surgery: Beneficial or Useless?

Omega-3 polyunsaturated fatty acids (w-3 PUFAs) are essential nutrients for human beings and their potential roles against cancer development and progression have become of wide concern recently. Some studies have suggested that perioperative supplementation with omega-3 fatty acids may have beneficial effects in gastrointestinal cancer patients undergoing surgery, while other researchers reported contrary results. This paper reviews recent research to establish therapeutic effects as well as possible underlying mechanisms of ????PUFA actions, and to help explain possible reasons for inconsistent results from different institutions.

Activated protein C and septic shock

Septic shock is a highly inflammatory and procoagulant state associated with significant mortality. In a single randomized controlled trial, recombinant human activated protein C (drotrecogin alfa) reduced mortality in patients with severe sepsis at high risk of death. Further clinical trials, including a recently completed trial in patients with septic shock, failed to reproduce these results. To evaluate the effectiveness of recombinant human activated protein C on mortality in a cohort of patients with septic shock and to explore possible reasons for inconsistent results in previous studies. Retrospective, 2:1 propensity-matched, multicenter cohort study. Twenty-nine academic and community intensive care units in three countries. Seven thousand three hundred ninety-two adult patients diagnosed with septic shock, of which 349 received recombinant human activated protein C within 48 hrs of intensive care unit admission between 1997 and 2007. Our primary outcomes were mortality over 30 days and mortality stratified by Acute Physiology and Chronic Health Evaluation II quartile. Using a propensity-matched Cox proportional hazard model, we observed a 6.1% absolute reduction in 30-day mortality associated with the use of recombinant human activated protein C (108/311 [34.7%] vs. 254/622 [40.8%], hazard ratio 0.72, 95% confidence interval 0.52-1.00, p = .05) and noted consistent reductions in mortality among Acute Physiology and Chronic Health Evaluation II quartiles. A time to event analysis showed that the time to appropriate antimicrobials after documented hypotension decreased for each year of study (p = .003), a finding that was congruent with a decrease in annual mortality over the study period (odds ratio 0.96 per year [95% confidence interval 0.93-0.99], p = .003). In this retrospective, propensity-matched, multicenter cohort study of patients with septic shock, early use of recombinant human activated protein C was associated with reduced mortality. Improvements in general quality of care such as speed of antimicrobial delivery leading to decreasing mortality of patients with septic shock may have contributed to the null results of the recently completed trial of recombinant human activated protein C in patients with septic shock.

Comparison of risky decision-making and evaluation of riskiness of women and men

It was noticed that there are not consistent findings about specificity in risky decision-making among women and men. For this reason, the research of gender differences in risky decision-making and the perception of risk was conducted. Two different techniques (paired-comparisons method and choosing risky or safe decision of problem situation) were used in order to find if men are more risk-taking than women and if they rate risky work situations in the same manner as women. The subjects were ninety working students from Lithuanian universities. The results were inconsistent. In some cases men were more risk-taking than women, but the ratings of risky work situations were very similar for both - men and women. The advantages and limitations of the research, possible reasons for inconsistent results were discussed and the suggestions for future research were given.

New serotype of Bartonella heriselae in endocarditis and cat-scratch disease

SummaryBackground The fastidious nature of Bartonella henselae is such that demonstration of clinical infection relies mainly on serological or molecular biological methods. Only five isolates have been obtained from patients with cat-scratch disease (CSD) and none from endocarditis.Methods We isolated B henselae from a CSD patient and, for the first time, from a patient with endocarditis. The isolates were characterised on the basis of morphology, biochemistry, cell-wall fatty-acid analysis, PCR-restriction fragment length polymorphism analysis of the 16-23S intragenic spacer region, and 16S rRNA gene sequences. Characterisation of these isolates indicated them to belong to a new serogroup, which we have called "Marseille", and to a new genotype based on the 16S rRNA gene sequence. The new variant was incorporated into an immunofluorescence antibody test (IFAT), which was used to reassess serum samples from 113 CSD patients who were seronegative with the conventional IFAT.Findings 18 (16%) of these apparently seronegative patients yielded significantly raised titres. 20 CSD patients who were seropositive as judged by the conventional IFAT remained seropositive with the new IFAT.Interpretation Antigenic variability within the species is one possible reason for inconsistent results in the serological diagnosis of CSD.