Expression and characterization of the eaeA gene product of Escherichia coli serotype O157:H7.

In enteropathogenic Escherichia coli, the eaeA gene produces a 94-kDa outer membrane protein called intimin which has been shown to be necessary but not sufficient to produce the attaching-and-effacing lesion. The purpose of this study was to characterize the intimin specified by the eaeA allele of the enterohemorrhagic E. coli (EHEC) serotype O157:H7 strain CL8 and to determine its role in adherence. The carboxyl-terminal 266 amino acids of the CL8 intimin were expressed as a protein fusion with glutathione S-transferase, which was used to raise antiserum in rabbits. The antiserum reacted in Western immunoblots with a 97-kDa outer membrane protein of EHEC strains of serogroups O5, O26, O111, and O157 and enteropathogenic E. coli strains of serogroups O55 and O127. Surface labelling of CL8 with 125I showed that intimin was surface exposed. An eaeA insertional inactivation mutant of CL8 was produced and was designated CL8-KO1. Total adherence of CL8-KO1 to HEp-2 cells was not significantly different from that of CL8, but CL8-KO1 gave a negative result in the fluorescent actin staining test. The eaeA gene expressed alone in E. coli HB101 also gave a negative fluorescent actin staining test result. The eaeA gene of CL8 was able to complement the eaeA deletion mutation in CVD206. We conclude that the product of the EHEC eaeA gene is a 97-kDa surface-exposed protein and propose that it be designated intiminO157. Sherman et al. described a 94-kDa outer membrane protein which played an important role in adherence of E. coli O157:H7 (Infect. Immun. 59:890-899, 1991). Western immunoblotting and indirect fluorescent antibody studies showed that the protein described by Sherman et al. is not intimin.     

Peer influence on students’ estimates of performance: social comparison in clinical rotations

Context During clinical rotations, students move from one clinical situation to another. Questions exist about students’ strategies for coping with these transitions. These strategies may include a process of social comparison because in this context it offers the student an opportunity to estimate his or her abilities to master a novel rotation. These estimates are relevant for learning and performance because they are related to self‐efficacy. We investigated whether student estimates of their own future performance are influenced by the performance level and gender of the peer with whom the student compares him‐ or herself. Methods We designed an experimental study in which participating students (n = 321) were divided into groups assigned to 12 different conditions. Each condition entailed a written comparison situation in which a peer student had completed the rotation the participant was required to undertake next. Differences between conditions were determined by the performance level (worse, similar or better) and gender of the comparison peer. The overall grade achieved by the comparison peer remained the same in all conditions. We asked participants to estimate their own future performance in that novel rotation. Differences between their estimates were analysed using analysis of variance (anova) . Results Students’ estimates of their future performance were highest when the comparison peer was presented as performing less well and lowest when the comparison peer was presented as performing better (p < 0.001). Estimates of male and female students in same‐gender comparison conditions did not differ. In two of three opposite‐gender conditions, male students’ estimates were higher than those of females (p < 0.001 and p < 0.05, respectively). Conclusions Social comparison influences students’ estimates of their future performance in a novel rotation. The effect depends on the performance level and gender of the comparison peer. This indicates that comparisons against particular peers may strengthen or diminish a student’s self‐efficacy, which, in turn, may ease or hamper the student’s learning during clinical rotations. The study is limited by its experimental design. Future research should focus on students’ comparison behaviour in real transitions.     

Tacrolimus for the prevention and treatment of rejection of solid organ transplants

Since its introduction to the antirejection armamentarium in 1994, tacrolimus has become the workhorse of transplant professionals for avoidance of solid organ transplant rejection. Not only does tacrolimus have potent immunosuppressive qualities that prevent rejection, but dosing is straight forward and it is generally well tolerated. However, in the long term, conditions such as calcineurin inhibitor nephrotoxicity can become a problem. A discussion of the compound, the pharmacokinetics, history, and current approved uses for tacrolimus is described. Indeed, tacrolimus is the most important drug for preventing transplant rejection. However, the increased appreciation for significant side effects, particularly in the long term, has led to building interest in new agents with different mechanisms of action and different metabolism.     

Music-based memory enhancement in Alzheimer's Disease: Promise and limitations

In a previous study (Simmons-Stern, Budson & Ally, 2010), we found that patients with Alzheimer's disease (AD) better recognized visually presented lyrics when the lyrics were also sung rather than spoken at encoding. The present study sought to further investigate the effects of music on memory in patients with AD by making the content of the song lyrics relevant for the daily life of an older adult and by examining how musical encoding alters several different aspects of episodic memory. Patients with AD and healthy older adults studied visually presented novel song lyrics related to instrumental activities of daily living (IADL) that were accompanied by either a sung or a spoken recording. Overall, participants performed better on a memory test of general lyric content for lyrics that were studied sung as compared to spoken. However, on a memory test of specific lyric content, participants performed equally well for sung and spoken lyrics. We interpret these results in terms of a dual-process model of recognition memory such that the general content questions represent a familiarity-based representation that is preferentially sensitive to enhancement via music, while the specific content questions represent a recollection-based representation unaided by musical encoding. Additionally, in a test of basic recognition memory for the audio stimuli, patients with AD demonstrated equal discrimination for sung and spoken stimuli. We propose that the perceptual distinctiveness of musical stimuli enhanced metamemorial awareness in AD patients via a non-selective distinctiveness heuristic, thereby reducing false recognition while at the same time reducing true recognition and eliminating the mnemonic benefit of music. These results are discussed in the context of potential music-based memory enhancement interventions for the care of patients with AD.     

Response to traditional disease-modifying anti-rheumatic drugs in indigent South Africans with early rheumatoid arthritis

The clinical response to traditional disease-modifying anti-rheumatic drugs (DMARDs) in indigent South Africans with early rheumatoid arthritis was investigated. A cohort of patients with early (≤2 years) RA who were DMARD-naïve at inception were prospectively assessed for response to DMARDs using the Simplified Disease Activity Index (SDAI) over a 12-month period. Patients with low disease activity (LDA) at 12 months were compared to those with moderate and high disease activity with respect to demographic, clinical, autoantibody and radiographic features. The 171 patients (140 females) had a mean (SD) age of 47.1 (12.4) years, symptom duration of 11.7 (7.1) months and baseline SDAI of 39.4 (16.2). There was a significant overall improvement in the SDAI and its components in the 134 (78.4%) patients who completed the 12 months visit, but only 28.4% of them achieved LDA. The majority of patients (91%) were treated with methotrexate as monotherapy or in combination with chloroquine and/or sulphasalazine. Baseline features that independently predicted a LDA state at 12 months were lower Health Assessment Questionnaire Disability Index (p?=?0.023) and a higher haemoglobin level (p?=?0.048). Receiver operating characteristic curve analysis showed that the 6-month SDAI was better than the baseline SDAI in predicting the 12-month SDAI (area under the curve of 0.69 vs. 0.52, respectively, p?=?0.008). In conclusion, less than a third of the patients achieved a low disease activity at 12 months on traditional DMARDs. Patients who have an inadequate response to traditional DMARDs at 6 months are unlikely to show further improvement on traditional DMARDs at 12 months. These findings underscore the need for better disease control by an aggressive tight control strategy, including intense patient education and biologic therapy.     

γ-Aminobutyric acid (GABA) concentration inversely correlates with basal perfusion in human occipital lobe

Commonly used neuroimaging approaches in humans exploit hemodynamic or metabolic indicators of brain function. However, fundamental gaps remain in our ability to relate such hemo-metabolic reactivity to neurotransmission, with recent reports providing paradoxical information regarding the relationship among basal perfusion, functional imaging contrast, and neurotransmission in awake humans. Here, sequential magnetic resonance spectroscopy (MRS) measurements of the primary inhibitory neurotransmitter, γ-aminobutyric acid (GABA+macromolecules normalized by the complex N-acetyl aspartate-N-acetyl aspartyl glutamic acid: [GABA⁺]/[NAA–NAAG]), and magnetic resonance imaging (MRI) measurements of perfusion, fractional gray-matter volume, and arterial arrival time (AAT) are recorded in human visual cortex from a controlled cohort of young adult male volunteers with neurocognitive battery-confirmed comparable cognitive capacity (3 T; n=16; age=23±3 years). Regression analyses reveal an inverse correlation between [GABA⁺]/[NAA–NAAG] and perfusion (R=−0.46; P=0.037), yet no relationship between AAT and [GABA⁺]/[NAA–NAAG] (R=−0.12; P=0.33). Perfusion measurements that do not control for AAT variations reveal reduced correlations between [GABA⁺]/[NAA–NAAG] and perfusion (R=−0.13; P=0.32). These findings largely reconcile contradictory reports between perfusion and inhibitory tone, and underscore the physiologic origins of the growing literature relating functional imaging signals, hemodynamics, and neurotransmission.     

Chronic Proton Pump Inhibitor Therapy Associated with Increased Development of Fundic Gland Polyps

Background  

Fundic gland polyps (FGP) have been implicated with long-term proton pump inhibitor (PPI) use.