Associative recognition in mild cognitive impairment: Relationship to hippocampal volume and apolipoprotein E

Associative memory involves remembering relations between items of information and is critically dependent on the hippocampus, a brain structure that shows early changes in amnestic mild cognitive impairment (aMCI) and Alzheimer's disease. We examined associative and item memory in aMCI with a focus on the role of medial-temporal lobe regions and genetic risk for Alzheimer's disease. Twenty-four individuals with aMCI and 21 demographically matched healthy older adults underwent associative recognition testing, structural brain imaging, and apolipoprotein E (ApoE) genotyping. A significant interaction between group and recognition type indicated poorer associative recognition than item recognition across tasks in the aMCI group relative to controls. Within the aMCI group, associative but not item recognition showed sizable and significant correlations with hippocampal volume (but not with other medial temporal-lobe structures) and with number of ApoE ε4 alleles. Correlations were smaller and generally not significant in the control group. Our findings replicate and extend previous studies by showing an associative recognition impairment in aMCI that is not accounted for by an item recognition deficit, is related to structural integrity of the hippocampus, and increases with genetic risk for Alzheimer's disease.     

Psychometric properties of the Actual Week test: a naturalistic prospective memory task

Objective: Prospective memory is the ability to ‘remember to remember’ and a facet of memory important to everyday functioning. For older adults, prospective memory slips are a common concern. In the present study, we conducted an initial validation of a paper-and-pencil adaptation of the Actual Week test, and reported on internal consistency, inter-rater and test-retest reliability, convergent and divergent validity, as well as veridicality of the task. Method: Fifty-eight healthy, community-dwelling older adults were recruited from a larger randomized controlled trial and tested at baseline. The Actual Week test was a naturalistic five-day prospective memory task where participants were assigned eight hypothetical tasks to remember per day for five days. Tasks were either time-cued or event-cued and regular (i.e. occurring daily) or irregular (i.e. varied each day). The proportion of tasks that were recorded as on time and accurate was used as the primary measure of performance. Results: The Actual Week test had good internal consistency (Kuder–Richardson: r > .8), intra-test (intraclass correlation: α > .9) and test-retest reliability (r = .76). There was also evidence for convergent and divergent validity. Task performance was associated with age, but not years of education or sex. Conclusion: The Actual Week test demonstrated strong psychometric qualities and promising evidence for validity as a performance-based measure of everyday prospective memory in older adults. Avenues for future studies include extending the evidence for convergent validity and evaluating feasibility and utility with other clinical populations.     

Patient outcomes following wrist ganglion excision surgery

We present patient outcomes following surgical excision of primary wrist ganglia over a 5 year period. Patients (48 of 59; 81%) responded to a questionnaire by post or telephone, with a mean time to follow-up of 44 (range 21-77) months. There was a statistically significant reduction in all reported symptoms, including pain, paraesthesia, weakness, stiffness, and cosmesis. The recurrence rate was 8%. In total, 98% of patients were satisfied or very satisfied with treatment. Surgical excision of primary wrist ganglia may have advantages over aspiration and reassurance alone, particularly in reducing recurrence and hastening resolution of symptoms.     

Impairments in prospective and retrospective memory following stroke

Prospective memory (PM) is the ability to carry out a planned intention at a future time. We studied PM deficits in a group of community-dwelling stroke survivors compared with normal controls. Twelve stroke patients and 12 matched controls performed a series of tests assessing executive function, prospective (PM) and retrospective memory (RM). Patients performed less well than controls on laboratory measures of PM and associative RM; they also showed deficits on standard tests of RM and executive control. The groups did not differ on more structured clinical measures of executive function, RM, PM or self-rated PM and RM. The results are discussed in terms of an impairment in the ability to ‘self-initiate’ effortful cognitive processes.     

Dermatophytic defensin with antiinfective potential

Fungi are a newly emerging source of peptide antibiotics with therapeutic potential. Here, we report 17 new fungal defensin-like peptide (fDLP) genes and the detailed characterization of a corresponding synthetic fDLP (micasin) from a dermatophyte in terms of its structure, activity and therapeutic potential. NMR analysis showed that synthetic micasin adopts a "hallmark" cysteine-stabilized α-helical and β-sheet fold. It was active on both gram-positive and gram-negative bacteria, and importantly it killed two clinical isolates of methicillin-resistant Staphylococcus aureus and the opportunistic pathogen Pseudomonas aeruginosa at low micromolar concentrations. Micasin killed approximately 100% of treated bacteria within 3 h through a membrane nondisruptive mechanism of action, and showed extremely low hemolysis and high serum stability. Consistent with these functional properties, micasin increases survival in mice infected by the pathogenic bacteria in a peritonitis model. Our work represents a valuable approach to explore novel peptide antibiotics from a large resource of fungal genomes.     

Enhancing research use through online action research

BACKGROUND: Many health professionals, including occupational therapists, have difficulty utilizing research findings in daily practice. PURPOSE: To determine if an online action research project could enhance research use among occupational therapists working in similar practice areas. METHODS: Four groups of 12-14 occupational therapists met online for approximately one year. They discussed barriers and facilitators to research utilization, defined practice questions, and attempted to search for, synthesize and apply relevant research findings. Online communications and post-group interviews were thematically analyzed. RESULTS: Only half of the participants who began the project were still online with the research project at completion. These participants believed that their involvement in the group led to increased personal awareness, motivation and confidence regarding the use of research evidence in practice and knowledge to be used in practice. Time to review, critique and synthesize research evidence continued to be a major barrier to enhanced research utilization. PRACTICE IMPLICATIONS: Online meetings designed to enhance research use among occupational therapists appear to hold some promise, but refinements are needed to ensure their ultimate success.     

An examination of the effects of stimulus type, encoding task, and functional connectivity on the role of right prefrontal cortex in recognition memory

Right anterior prefrontal cortex and other brain areas are active during memory retrieval but the role of prefrontal cortex and how it interacts with these other regions to mediate memory function remain unclear. To explore these issues we used positron emission tomography to examine the effects of stimulus material and encoding task on brain activity during visual recognition, assessing both task-related changes and functional connectivity. Words and pictures of objects were encoded using perceptual and semantic strategies, resulting in better memory for semantically encoded items. There was no significant effect of prior encoding strategy on brain activity during recognition. Right anterior prefrontal cortex was equally active during recognition of both types of stimuli irrespective of initial encoding strategy. Regions whose activity was positively correlated with activity in right anterior prefrontal cortex included widespread areas of prefrontal and inferior temporal cortices bilaterally. Activity in this entire network of regions was negatively correlated with recognition accuracy of semantically encoded items. These results suggest that initial encoding task has little impact on the set of brain regions that is active during subsequent recognition. Right anterior prefrontal cortex appears to be involved in retrieval mode, reflected in its equivalent activity across conditions differing in both stimulus type and encoding task, and also in retrieval effort, shown by the negative correlation between its functional connectivity and individual differences in recognition accuracy.     

Home-based leg-strengthening exercise improves function 1 year after hip fracture: a randomized controlled study

OBJECTIVES: To compare the effectiveness of a short‐term leg‐strengthening exercise program with that of attentional control on improving strength, walking abilities, and function 1 year after hip fracture. DESIGN: Randomized controlled pilot study. SETTING: Patients' homes. PARTICIPANTS: Community‐dwelling older adults (n=26) 6 months after hip fracture at baseline. INTERVENTION: Exercise and control participants received interventions from physical therapists twice a week for 10 weeks. The exercise group received high‐intensity leg‐strengthening exercises. The control group received transcutaneous electrical nerve stimulation and mental imagery. MEASUREMENTS: Isometric force production of lower extremity muscles, usual and fast gait speed, 6‐minute walk (6‐MW) distance, modified Physical Performance Test (mPPT), and Medical Outcomes Study 36‐item Short Form Survey (SF‐36) physical function. RESULTS: The primary endpoint was 1 year after fracture. Isometric force production (P=.006), usual (P=.02) and fast (P=.03) gait speed, 6‐MW distance (P=.005), and mPPT score (P<.001) were improved 1 year after fracture with exercise. Effect sizes were 0.79 for strength, 0.81 for mPPT score, 0.56 for gait speed, 0.49 for 6‐MW, and 0.30 for SF‐36 score. More patients in the exercise group made meaningful changes in gait speed and 6‐MW distance than control patients (chi‐square P=.004). CONCLUSION: A 10‐week home‐based progressive resistance exercise program was sufficient to achieve moderate to large effects on physical performance and quality of life and may offer an alternative intervention mode for patients with hip fracture who are unable to leave home by 6 months after the fracture. The effects were maintained at 3 months after completion of the training program.     

Plasma lipoproteins in visceral leishmaniasis and their effect on Leishmania‐infected macrophages

This work aimed at investigating the lipid profile of zoonotic visceral leishmaniasis (VL) patients’ sera and the effect of lipoproteins on the in vitro production of tumour necrosis factor‐α (TNF‐α), interleukin (IL)‐6, IL‐10 and IL‐12 by Leishmania infantum‐infected and uninfected macrophages. Lipids were quantified in 26 VL patients’ sera and 26 healthy controls from a VL endemic area. The patients’ sera had higher triglyceride and very low density lipoprotein (VLDL) levels, and much lower apolipoprotein A1, total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) levels than the control sera. Lipoprotein fractions were obtained by ultracentrifugation of sera. The addition of LDL and HDL to Leishmania‐infected and uninfected macrophages, in physiological concentrations, enhanced the production of IL‐6 and IL‐10, but not of IL‐12. LDL stimulated the production of TNF‐α only in infected macrophages, whereas HDL stimulated the production of lower amounts of TNF‐α in both infected and uninfected macrophages. VLDL stimulated only the production of IL‐10. It is proposed herein that LDL may influence the development of VL by promoting the production of TNF‐α by infected macrophages. A decrease in plasma LDL in some VL patients (to 20 mg/mL or less); however, would tend to reduce the production of TNF‐α and therefore to limit the development of immune‐mediated pathology, not withstanding the fact that it would perhaps increase the permissiveness of macrophages to Leishmania growth.     

NMR measurement of 39K detectability and relaxation constants in rat tissue

Differences in the NMR detectability of ³⁹K in various excised rat tissues (liver, brain, kidney, muscle, and testes) have been observed. The lowest NMR detectability occurs for liver (61 ± 3% of potassium as measured by flame photometry) and highest for erythrocytes (100 ± 7%). These differences in detectability correlate with differences in the measured ³⁹K NMR relaxation constants in the same tissues. ³⁹K detectabilities were also found to correlate inversely with the mitochondrial content of the tissues. Mitochondria prepared from liver showed greatly reduced ³⁹K NMR detectability when compared with the tissue from which it was derived, 31.6 ± 9% of potassium measured by flame photometry compared to 61 ± 3%. The detectability of potassium in mitochondria was too low to enable the measurement of relaxation constants. This study indicates that differences in tissue structure, particularly mitochondrial content are important in determining ³⁹K detectability and measured relaxation rates.