Levels of analysis issues in group psychology: Using efficacy as an example of a multilevel model.

Levels of analysis issues have attracted a lot of attention in group psychology research. Despite assertions pertaining to the value of multilevel models, most researchers focus on either the individual within groups or the group as a whole, but seldom on both. A multilevel approach may be helpful to group psychologists. This article addresses levels of analysis issues that are an inherent part of group research, and a number of methods that can be used to analyze multilevel data are presented. The methods fall into 3 categories: (a) assessing the extent of agreement within a single group, (b) contrasting within-group and between-groups variance, and (c) conducting multiple-level analyses. Finally, recommendations are offered for future multilevel research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of eosinophils and neutrophils in helminth-induced keratitis

PURPOSE: Intrastromal injection of mice with antigens from the parasitic helminth that causes river blindness (Onchocerca volvulus) induces eosinophil recruitment to the corneal stroma at the time of maximum corneal opacification and neovascularization. The present study was conducted to examine the role of eosinophils and neutrophils in onchocercal keratitis in control C57Bl/6 mice and in interleukin-5 gene knockout (IL-5(-/-)) mice. METHODS: C57Bl/6 and IL-5(-/-) mice were immunized subcutaneously and injected intrastromally with soluble O. volvulus antigens. Mice were killed at various times thereafter. Development of keratitis was assessed by slit lamp examination, and inflammatory cells in the cornea were identified by immunohistochemistry. RESULTS: A biphasic recruitment of inflammatory cells was observed in C57Bl/6 mice; neutrophils predominated during the first 72 hours after intrastromal injection and subsequently declined, whereas eosinophil recruitment increased as time elapsed and comprised the majority (90%) of cells in the cornea by day 7. In contrast, neutrophils were the predominant inflammatory cells in IL-5(-/-) mice at early and late time points and were associated with extensive stromal damage and corneal opacification and neovascularization. Eosinophils were not detected in these mice at any time. CONCLUSIONS: In the absence of eosinophils, neutrophils can mediate keratitis induced by helminth antigens. Together with the early neutrophilic infiltrate in control animals, these observations indicate that neutrophils have an important role in onchocercal keratitis.     

Use of cumulative meta-analysis in the design, monitoring, and final analysis of a clinical trial: a case study

From 1983 to 1987, the Department of Veterans Affairs (DVA) Cooperative Studies Program (CSP) conducted a multicenter clinical trial (CSP #207) to determine whether four different antiplatelet regimens compared to placebo could prevent the occlusion of grafts following coronary artery bypass surgery. The study showed that all of the active regimens tended to be better than placebo and that the three regimens containing aspirin were statistically significantly better. A cumulative meta-analysis of 12 trials performed shortly before the end of CSP #207 raised the issue as to whether the meta-analysis, if done earlier, would have changed the conduct of the trial. At the start of the planning period, one trail of size n = 37 had been published with a nonsignificant odds ratio (OR) of 0.74 (95% CI: 0.18, 3.12). At the time that CSP # 207 was approved by the DVA Cooperative Studies Evaluation Committee, two trials had been published (cumulative n = 150, OR = 0.44, 95% CI 0.19, 0.99). At the time patient intake started, five trials showed cumulative n = 769, OR = 0.42, 95% CI = 0.26, 0.68. Although the first 6-month CSP #207 progress report showed no treatment effect, by the time of the 12-month review by the Data Monitoring Board (DMB) a trend was developing in favor of active treatment. If the results of the meta-analysis had been available to the DMB at that time, conceivably the Board would have recommended stopping the placebo arm because of a convincing treatment effect based on the totality of the evidence. Cumulative meta-analysis could be useful as an adjunct in the planning, conduct, and final analysis of a clinical trial. It could also be used as one piece of evidence in the monitoring of the ongoing phase of a trial.     

Learning and chronobiological regulation following experimental damage to the coronary-artery wall of albino rats]

Forty male albino rats were used to study the relationship between experimentally (concentrated hydrochloric acid) produced local structural changes of the coronary artery wall and central nervous information processing and chronobiological events, respectively. The alterations of the coronary arteries caused by this treatment did not produce infarction but initiated on the whole length of the arterial branch proliferative processes that are complete within 12 weeks following the intervention. Central nervous information processing and chronoregulatory processes showed, immediately after exposure to hydrochloric acid, pronounced malfunctions followed by a stage of hyperreactivity (4 weeks following the damage). At 8 weeks from the intervention, the parameters of information processing and chronobiological events of the CNS again equalled the control values. Since the central nervous functions were back to normal earlier than the structural alterations, the results are interpreted as reflecting CNS-controlled interactions between the complex of visceral afference and efference, the regulation of which is determined by the CNS after coronary damage in such a way as to restore the adaptational capacity of the organism by a predominance of sanogenetic processes.     

High-throughput data analysis for detecting and identifying differences between samples in GC/MS-based metabolomic analyses

In metabolomics, the objective is to identify differences in metabolite profiles between samples. A widely used tool in metabolomics investigations is gas chromatography-mass spectrometry (GC/MS). More than 400 compounds can be detected in a single analysis, if overlapping GC/MS peaks are deconvoluted. However, the deconvolution process is time-consuming and difficult to automate, and additional processing is needed in order to compare samples. Therefore, there is a need to improve and automate the data processing strategy for data generated in GC/MS-based metabolomics; if not, the processing step will be a major bottleneck for high-throughput analyses. Here we describe a new semiautomated strategy using a hierarchical multivariate curve resolution approach that processes all samples simultaneously. The presented strategy generates (after appropriate treatment, e.g., multivariate analysis) tables of all the detected metabolites that differ in relative concentrations between samples. The processing of 70 samples took similar time to that of the GC/TOFMS analyses of the samples. The strategy has been validated using two different sets of samples: a complex mixture of standard compounds and Arabidopsis samples.     

The use of isolated vowels as auditory stimuli in eliciting the verbal transformation effect.

Determined the effectiveness of single isolated vowels as auditory stimuli in eliciting perceptual illusory changes in ss, a phenomenon referred to by R. M. Warren (see pa, vol. 36:3gh49w) as the "verbal transformation effect." 3 vowels, /i/, /ae/, and /u/, were individually presented to a group of 24 19-24 yr. Old normal listeners in a single experimental session. Each vowel was repeatedly presented by means of headphones for a period of 5 min. Results indicate that single isolated vowels are capable of eliciting verbal transformations in normal listeners. However, the transformations reported often differed from those obtained in previous studies which used more phonetically complex auditory stimuli. The nature of the verbal transformations, average number of alternate forms perceived and transitions employed, and average number of repetitions of the stimuli prior to the onset of the ss' 1st verbal transformations are discussed. Comparisons with findings of previous investigations are provided. (french summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)