Modulation of working memory load distinguishes individuals with and without balance impairments following mild traumatic brain injury.

OBJECTIVES: Balance and gait deficits can persist after mild traumatic brain injury (TBI), yet an understanding of the underlying neural mechanism remains limited. The purpose of this study was to investigate differences in attention network modulation in patients with and without balance impairments 2-8 weeks following mild TBI. METHODS: Using functional magnetic resonance imaging, we compared activity and functional connectivity of cognitive brain regions of the default mode, central-executive and salience networks during a 2-back working memory task in participants with mild TBI and balance impairments (n = 7, age 47 ± 15 years) or no balance impairments (n = 7, age 47 ± 15 years). RESULTS: We first identified greater activation in the lateral occipital cortex in the balance impaired group. Second, we observed stronger connectivity of left pre-supplementary motor cortex in the balance impaired group during the working memory task, which was related to decreased activation of regions within the salience and central executive networks and greater suppression of the default mode network. CONCLUSIONS: Results suggest a link between impaired balance and modulation of cognitive resources in patients in mTBI. Findings also highlight the potential importance of moving beyond traditional balance assessments towards an integrative assessment of cognition and balance in this population.

Neural and Muscular Contributions to the Age-Related Reductions in Rapid Strength.

INTRODUCTION: The purposes of this study were to investigate the age-related differences in absolute and normalized plantarflexion rate of torque development (RTD) at early (0-50 ms) and late (100-200 ms) time intervals and to examine specific neural and muscular mechanisms contributing to these differences. METHODS: Thirty-two young (20.0 ± 2.1 yr) and 20 older (69.5 ± 3.3 yr) recreationally active men performed rapid plantarflexion isometric muscle actions to examine absolute and normalized RTD and muscle activation using EMG at early and late time intervals. Ultrasonography was used to examine medial gastrocnemius muscle size, echo intensity (EI), and muscle architecture (fascicle length [FL] and pennation angle [PA]). RESULTS: The older men were weaker (23.9%, P < 0.001) and had lower later absolute and normalized RTD (P = 0.001-0.034) variables when compared with the young men. The older men also had higher EI (P < 0.001), smaller PA (P = 0.004), and lower later EMG amplitude values (P = 0.009-0.046). However, there were no differences in early RTD and EMG amplitude values, muscle size, or FL between groups (P = 0.097-0.914). Lower late RTD values were related to higher EI, smaller PA, and lower EMG amplitude values (r = -0.28-0.59, P = 0.001-0.044); however, late RTD values were no longer related to PA after normalizing to peak torque. CONCLUSIONS: Age-related alterations in muscle quality (EI), architecture, and muscle activation may influence rapid torque production at late time intervals (≥100 ms) from contraction onset. These findings highlight specific neuromuscular factors that influence the age-related reductions in RTD, which has been shown to significantly influence function and performance in older adults.

The influence of ultrasound measurement techniques on the age-related differences in Achilles tendon size.

Achilles tendon (AT) properties change with age, however the extent to which aging influences the size of the AT may be influenced by the measurement technique. The purpose of this study was to 1) examine the age-related differences in AT size using measures of cross-sectional area (CSA) and thickness, and 2) to determine the test-retest reliability and minimum difference (MD) values of these measures. The size of the AT was examined in 19 young (19.79 ± 2.3 years) and 18 older (69.4 ± 3.1 years) healthy men on two separate occasions using an ultrasonography. The CSA and thickness of the AT were determined by separate transverse and longitudinal scans on the right leg at the same distance from the medial malleolus, respectively. Prior to and after accounting for body mass, AT CSA was larger (P ≤ 0.01) in the older men (64.49 ± 13.87 mm(2)) when compared to the younger men (44.12 ± 16.04 mm(2)), however there were no differences in AT thickness between age groups (P=0.96). In addition, there was no systematic error (P>0.05) between testing days, and the intraclass correlation coefficients, standard error of measurement (expressed as a % of the mean), and MD values for CSA and thickness ranged from 0.80-0.98, 5.46-8.68%, and 5.65-7.94 mm(2) and 0.51-0.86 mm, respectively between both groups. These findings suggest that the reliability of the CSA and thickness measurements were similar, however, CSA was a more sensitive measure to detect the age-related changes of AT size.

Pennation angle does not influence the age-related differences in echo intensity of the medial gastrocnemius.

The reflection of an ultrasound (US) wave is strongest when the propagation direction of the wave is perpendicular to muscle fascicles. Thus, it is possible that muscle echo intensity (EI), a gray-scale US measure of muscle quality, may be influenced by the angulation of muscle fascicles. Therefore, the purpose of this study was to determine if age-related differences in muscle EI values are influenced by differences in pennation angle (PA). Medial gastrocnemius EI and PA were examined using panoramic US imaging in 24 young (19.8 ± 1.7 y) and 21 older (69.3 ± 3.3 y) men. The young men had lower EI values (young = 74.1 ± 6.3 a.u., older = 89.1 ± 8.8 a.u.) and a greater PA (young = 20.0 ± 2.9°; older = 17.2 ± 2.5°) compared with the older men (p < 0.01). In addition, there was a negative relationship (r = -0.473, p < 0.01) between PA and EI with both groups combined, but no significant relationship when the young (r = -0.334, p = 0.111) and older (r = -0.147, p = 0.525) men were examined separately. An analysis of covariance revealed that muscle EI values remained different (p < 0.01) between age groups after adjustment for differences in PA. Thus, after statistically adjusting the mean EI values for the differences in PA, there were still significant age-related differences in EI. These findings may provide further support that the age-related changes in muscle EI values reflect changes in tissue composition (i.e., increase in intramuscular fat and/or connective tissue) commonly reported in older adults.

Associations between interhemispheric functional connectivity and the Automated Neuropsychological Assessment Metrics (ANAM) in civilian mild TBI.

This study investigates cognitive deficits and alterations in resting state functional connectivity in civilian mild traumatic brain injury (mTBI) participants with high and low symptoms. Forty-one mTBI participants completed a resting state fMRI scan and the Automated Neuropsychological Assessment Metrics (ANAM) during initial testing (<10 days of injury) and a 1 month follow up. Data were compared to 30 healthy control subjects. Results from the ANAM demonstrate that mTBI participants performed significantly worse than controls on the code substitution delayed subtest (p = 0.032). [corrected]. Among the mTBI patients, high symptom mTBI participants performed worse than those with low symptoms on the code substitution delayed (p = 0.017), code substitution (p = 0.012), repeated simple reaction time (p = 0.031), and weighted throughput score (p = 0.019). [corrected]. Imaging results reveal that during the initial visit, low symptom mTBI participants had reduced interhemispheric functional connectivity (IH-FC) within the lateral parietal lobe (p = 0.020); however, during follow up, high symptom mTBI participants showed reduced IH-FC compared to the control group within the dorsolateral prefrontal cortex (DLPFC) (p = 0.013). Reduced IH-FC within the DLPFC during the follow-up was associated with reduced cognitive performance. Together, these findings suggest that reduced rs-FC may contribute to the subtle cognitive deficits noted in high symptom mTBI participants compared to control subjects and low symptom mTBI participants.

Comparison of the acute metabolic responses to traditional resistance, body-weight, and battling rope exercises.

The purpose of this study was to quantify and compare the acute metabolic responses to resistance exercise protocols comprising free-weight, body-weight, and battling rope (BR) exercises. Ten resistance-trained men (age = 20.6 ± 1.3 years) performed 13 resistance exercise protocols on separate days in random order consisting of only one exercise per session. For free-weight exercise protocols, subjects performed 3 sets of up to 10 repetitions with 75% of their 1 repetition maximum. For the push-up (PU) and push-up on a BOSU ball protocols, subjects performed 3 sets of 20 repetitions. For the burpee and PU with lateral crawl protocols, subjects performed 3 sets of 10 repetitions. For the plank and BR circuit protocols, subjects performed 3 sets of 30-second bouts. A standard 2-minute rest interval (RI) was used in between all sets for each exercise. Data were averaged for the entire protocol including work and RIs. Mean oxygen consumption was significantly greatest during the BR (24.6 ± 2.6 ml·kg·min) and burpee (22.9 ± 2.1 ml·kg·min) protocols. For the free-weight exercises, highest mean values were seen in the squat (19.6 ± 1.8 ml·kg·min), deadlift (18.9 ± 3.0 ml·kg·min), and lunge (17.3 ± 2.6 ml·kg·min). No differences were observed between PUs performed on the floor vs. on a BOSU ball. However, adding a lateral crawl to the PU significantly increased mean oxygen consumption (19.5 ± 2.9 ml·kg·min). The lowest mean value was seen during the plank exercise (7.9 ± 0.7 ml·kg·min). These data indicate performance of exercises with BRs and a body-weight burpee exercise elicit relatively higher acute metabolic demands than traditional resistance exercises performed with moderately heavy loading.

Using antibiograms to improve antibiotic prescribing in skilled nursing facilities.

BACKGROUND: Antibiograms have effectively improved antibiotic prescribing in acute-care settings; however, their effectiveness in skilled nursing facilities (SNFs) is currently unknown. OBJECTIVE: To develop SNF-specific antibiograms and identify opportunities to improve antibiotic prescribing. DESIGN AND SETTING: Cross-sectional and pretest-posttest study among residents of 3 Maryland SNFs. METHODS: Antibiograms were created using clinical culture data from a 6-month period in each SNF. We also used admission clinical culture data from the acute care facility primarily associated with each SNF for transferred residents. We manually collected all data from medical charts, and antibiograms were created using WHONET software. We then used a pretest-posttest study to evaluate the effectiveness of an antibiogram on changing antibiotic prescribing practices in a single SNF. Appropriate empirical antibiotic therapy was defined as an empirical antibiotic choice that sufficiently covered the infecting organism, considering antibiotic susceptibilities. RESULTS: We reviewed 839 patient charts from SNF and acute care facilities. During the initial assessment period, 85% of initial antibiotic use in the SNFs was empirical, and thus only 15% of initial antibiotics were based on culture results. Fluoroquinolones were the most frequently used empirical antibiotics, accounting for 54.5% of initial prescribing instances. Among patients with available culture data, only 35% of empirical antibiotic prescribing was determined to be appropriate. In the single SNF in which we evaluated antibiogram effectiveness, prevalence of appropriate antibiotic prescribing increased from 32% to 45% after antibiogram implementation; however, this was not statistically significant ([Formula: see text]). CONCLUSIONS: Implementation of antibiograms may be effective in improving empirical antibiotic prescribing in SNFs.

Acute oxygen uptake and resistance exercise performance using different rest interval lengths: the influence of maximal aerobic capacity and exercise sequence.

The purpose of this study was to examine the relationship between VO2max and acute resistance exercise performance and the acute metabolic effects of exercise sequencing. Seventeen resistance-trained men were tested for VO2max and 1 repetition maximum (1RM) strength. Subjects were randomly assigned to either a group that performed the squat first in sequence followed by the bench press (S; n = 8) or a group that performed the bench press first followed by the squat (BP; n = 9). Each group performed 3 protocols (using 1-, 2-, or 3-minute rest intervals [RIs] between sets in random order) consisting of 5 sets of each exercise with 75% of their 1RM for up to 10 repetitions while oxygen consumption was measured. Total repetitions completed were highest with 3-minute RI and lowest with 1-minute RI. Mean VO2 was significantly highest with 1-minute RI and lowest using 3-minute RI. Analysis of each exercise revealed a tendency (p = 0.07) for mean bench press VO2 to be higher when it was performed after the squat using 1- and 2-minute RIs. VO2max was significantly negatively correlated to 1RM bench press and squat (r = -0.79 and -0.60, respectively) and was significantly correlated to squat repetitions (r = 0.43-0.57) but did not correlate to bench press performance. It seems that VO2max is related to lower-body resistance exercise performance when short RIs are used, and the metabolic response to the bench press is augmented when it follows the squat in sequence using short RIs.

Depressive symptoms and hospital readmission in older adults.

OBJECTIVES: To quantify the risk of 30-day unplanned hospital readmission in adults aged 65 and older with depressive symptoms. DESIGN: Prospective cohort study. SETTING: University of Maryland Medical Center. PARTICIPANTS: Individuals aged 65 and older admitted between July 1, 2011, and August 9, 2012, to the general medical and surgical units and followed for 31 days after hospital discharge (N = 750). MEASUREMENTS: Primary exposure was depressive symptoms at admission, defined as a score of 6 or more on the 15-item Geriatric Depression Scale. Primary outcome was unplanned 30-day hospital readmission, defined as an unscheduled overnight stay at any inpatient facility not occurring in the emergency department. RESULTS: Prevalence of depressive symptoms was 19% and incidence of 30-day unplanned hospital readmission was 19%. Depressive symptoms were not significantly associated with hospital readmission (relative risk (RR) = 1.20, 95% confidence interval (CI) = 0.83-1.72). Age, Charlson Comorbidity Index score, and number of hospitalizations within the past 6 months were significant predictors of unplanned 30-day hospital readmission. CONCLUSION: Although not associated with hospital readmission, depressive symptoms were associated with other poor outcomes and may be underdiagnosed in hospitalized older adults. Hospitals interested in reducing readmission should focus on older adults with more comorbid illness and recent hospitalizations.

Longitudinal and prognostic evaluation of mild traumatic brain injury: A 1H-magnetic resonance spectroscopy study.

In the majority of patients with mild traumatic brain injury (mTBI), brain tissue impairment is undetectable by computed tomography and/or structural magnetic resonance imaging. Even in confirmed cases of head injury, conventional neuroimaging methods lack sensitivity in predicting neuropsychological outcomes of patients. The objectives of this study were to (1) cross-sectionally determine deviations in the neurometabolic profile of patients with mTBI from healthy controls at different stages of mTBI using tightly controlled examination windows, and (2) determine associations between acute neurometabolic markers of mTBI and chronic neurocognitive performance. Patients were examined at the early subacute (n=43; 5.44 ± 3.15 days post-injury (DPI)), late subacute (n=33; 37.00 ± 12.26 DPI) and chronic (n=27; 195.30 ± 19.60 DPI) stages of mTBI. Twenty-one neurologically intact subjects were used as controls. Proton magnetic resonance spectroscopy imaging ((1)H-MRSI) was used to obtain metabolic measurements from different brain regions. The Automated Neuropsychological Assessment Metrics (ANAM) was used for cognitive evaluation of patients at the chronic stage of mTBI. Measurements in the thalamus and centrum semiovale (CSV) emerged as the most indicative of injury and were used to predict neurocognitive outcome. The major findings of this study are (1) decreases in Cho/Cre (choline-to-creatine ratio) measured in the thalamus (p=0.042) and CSV (p=0.017) at the late subacute stage of mTBI; (2) positive associations of early subacute Cre measurements in the CSV with chronic ANAM scores measuring performance in delayed (r=0.497, p=0.019) and immediate (r=0.391, p=0.072) code substitution. These findings show that metabolic measurements in the thalamus and CSV can potentially serve as diagnostic and prognostic markers of mTBI.

Reliability of panoramic ultrasound imaging to simultaneously examine muscle size and quality of the medial gastrocnemius.

INTRODUCTION: In this study we examined the test-retest reliability of panoramic brightness-mode ultrasound (US) imaging to simultaneously measure both muscle size and quality from a single US image. METHODS: Sixteen healthy, recreationally active men (age = 20.9 ± 2.5 years) volunteered for this investigation. Test-retest reliability was evaluated using intraclass correlation coefficients (ICCs) and the standard error of measurement as a percentage of the mean (SEM%). Muscle size [cross-sectional area (CSA)], and muscle quality [echo intensity (EI)] of the medial gastrocnemius were examined on 2 separate days. RESULTS: These measures demonstrated acceptable reliability between assessment days with ICCs and SEM% of 0.914 and 0.720 and 5.830 and 3.680 for CSA and EI, respectively. CONCLUSIONS: These results suggest that panoramic US imaging may be a reliable technique for simultaneous assessment of both muscle size and quality from a single US scan.

Antimicrobial use for symptom management in patients receiving hospice and palliative care: a systematic review.

BACKGROUND: Patients receiving hospice or palliative care often receive antimicrobial therapy; however the effectiveness of antimicrobial therapy for symptom management in these patients is unknown. OBJECTIVE: The study's objective was to systematically review and summarize existing data on the prevalence and effectiveness of antimicrobial therapy to improve symptom burden among hospice or palliative care patients. DESIGN: Systematic review of articles on microbial use in hospice and palliative care patients published from January 1, 2001 through June 30, 2011. MEASUREMENTS: We extracted data on patients' underlying chronic condition and health care setting, study design, prevalence of antimicrobial use, whether symptom response following antimicrobial use was measured, and the method for measuring symptom response. RESULTS: Eleven studies met our inclusion criteria in which prevalence of antimicrobial use ranged from 4% to 84%. Eight studies measured symptom response following antimicrobial therapy. Methods of symptom assessment were highly variable and ranged from clinical assessment from patients' charts to the Edmonton Symptom Assessment Scale. Symptom improvement varied by indication, and patients with urinary tract infections (two studies) appeared to experience the greatest improvement following antimicrobial therapy (range 67% to 92%). CONCLUSION: Limited data are available on the use of antimicrobial therapy for symptom management among patients receiving palliative or hospice care. Future studies should systematically measure symptom response and control for important confounders to provide useful data to guide antimicrobial use in this population.

Test-retest reliability and the minimal detectable change for achilles tendon length: a panoramic ultrasound assessment.

The purpose of the present study was to examine test-retest reliability and minimal detectable change (MDC) values for Achilles tendon (AT) length determined using panoramic ultrasound (US) imaging. Seventeen men (age = 21.0 ± 2.3 y) visited the laboratory on two separate days, where AT length was examined along the mid-longitudinal axis of the right lower leg with a portable B-mode panoramic US device. These measures were found to have acceptable reliability with intra-class correlation coefficient (ICC) and standard error of measurement (SEM) values of 0.954 and 4.43 mm (SEM% of the mean = 2.37%), respectively. In addition, the MDC for the panoramic US assessment of AT length was 12.27 mm (MDC% of the mean = 6.57%). These findings suggest that panoramic US imaging is a reliable technique for detection of clinically relevant changes in AT length and may therefore be a practical and time-efficient clinical tool for future studies examining AT length in vivo.

Metabolic responses during postprandial exercise.

To examine metabolic interaction between meal and exercise, 10 men and 10 women completed three trials: (1) exercise (E), (2) consumption of a meal (M), and (3) consumption of a meal followed by exercise (M+E). All trials commenced after an overnight fast and were preceded by a rest period in which resting metabolic rate (RMR) was determined. The meal contained 721 kilocalories composed of 41%, 36%, and 23% of carbohydrate, lipids, and protein, respectively. Exercise protocol consisted of three continuous 10-minute cycling at 50%, 60%, and 70% VO2peak. Measurement began 60 min after the start of the meal and included VO2 that was used to determine meal-induced thermogenesis (MIT). VO2 was greater (p < .05) in M+E than in E at 50% and 60% VO2peak. MIT was higher (p < .05) during exercise at 50% VO2peak than at rest. It appears that postprandial exercise of mild intensities can potentiate MIT, thereby provoking a greater increase in energy expenditure.