On the Importance of Including Cohesive Zone Models in Modelling Mixed-Mode Aneurysm Rupture.

INTRODUCTION: The precise mechanism of rupture in abdominal aortic aneurysms (AAAs) has not yet been uncovered. The phenomenological failure criterion of the coefficient of proportionality between von Mises stress and tissue strength does not account for any mechanistic foundation of tissue fracture. Experimental studies have shown that arterial failure is a stepwise process of fibrous delamination (mode II) and kinking (mode I) between layers. Such a mechanism has not previously been considered for AAA rupture. METHODS: In the current study we consider both von Mises stress in the wall, in addition to interlayer tractions and delamination using cohesive zone models. Firstly, we present a parametric investigation of the influence of a range of AAA anatomical features on the likelihood of elevated interlayer traction and delamination. RESULTS: We observe in several cases that the location of peak von Mises stress and tangential traction coincide. Our simulations also reveal however, that peak von Mises and intramural tractions are not coincident for aneurysms with Length/Radius less than 2 (short high-curvature aneurysms) and for aneurysms with symmetric intraluminal thrombus (ILT). For an aneurysm with (L/R = 2.0), the peak σ vm moves slightly towards the origin while the peak T t is near the peak bulge with a separation distance of ~ 17 mm. Additionally, we present three patient-specific AAA models derived directly from CT scans, which also illustrate that the location of von Mises stress does not correlate with the point of interlayer delamination. CONCLUSION: This study suggests that incorporating cohesive zone models into clinical based FE analyses may capture a greater proportion of ruptures in-silico.

Evidence for the improvement of fatigue in fibromyalgia: A 4-week left dorsolateral prefrontal cortex repetitive transcranial magnetic stimulation randomized-controlled trial.

BACKGROUND: Fibromyalgia is a complex chronic disorder with few effective treatments currently available. One promising treatment option is repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique that has shown promise in disorders effecting the central nervous system. METHODS: We assessed the efficacy of a course of high-frequency (10 Hz) left-hemisphere dorsolateral prefrontal cortex (DLPFC) rTMS in 26 patients (14 active; 12 sham) with a diagnosis of fibromyalgia. Participants underwent a double-blind stimulation protocol of daily (Monday-Friday) rTMS sessions over four consecutive weeks (total of 20 sessions; 75 × 4-s 10 Hz trains at 120% resting motor threshold). Assessments were conducted at baseline, 4 weeks and at 1-month follow-up. RESULTS: Using mixed-model analysis we did not identify a group difference for our primary outcome measures. However, we found that patients in the active group compared to sham treatment group had significantly greater improvement in the Physical Fatigue (p = 0.045) and General Fatigue (p = 0.023) scales of the Multidimensional Fatigue Inventory-20 at the 1 month follow-up. In a responder analysis, we also found the active group was significantly more likely (2.84 times) to achieve a minimum 30% improvement in pain intensity ratings. (p = 0.024). CONCLUSIONS: High-frequency rTMS applied daily for 4 weeks to the left DLPFC induces significant relief from fatigue and a greater chance of clinically meaningful improvement in pain intensity in patients with fibromyalgia. These results suggest DLPFC rTMS may be a relevant therapy for fibromyalgia. SIGNIFICANCE: This study provides evidence that 4-weeks of daily rTMS to the left DLPFC is able to improve fatigue in fibromyalgia. This novel finding provides impetus for the further investigation of the utility of TMS approaches for the relief of fatigue, an otherwise difficult-to-treat symptom, in fibromyalgia and related disorders.

Neural evidence that conscious awareness of errors is reduced in depression following a traumatic brain injury.

Impaired error awareness is related to poorer outcome following traumatic brain injury (TBI). Error awareness deficits are also found in major depressive disorder (MDD), but have not been examined in the MDD that follows a TBI (TBI-MDD). This study assessed neural activity related to error awareness in TBI-MDD. Four groups completed a response inhibition task while EEG was recorded- healthy controls (N = 15), MDD-only (N = 15), TBI-only (N = 16), and TBI-MDD (N = 12). Error related EEG activity was compared using powerful randomisation statistics that included all electrodes and time points. Participants with TBI-MDD displayed less frontally distributed neural activity, suggesting reduced contribution from frontal generating sources. Neural activity during this time window is thought to reflect conscious awareness of errors. The TBI-only and MDD-only groups did not differ from controls, and early error processing was unaffected, suggesting early error detection is intact.

Affective, sensory and empathic sharing of another's pain: The Empathy for Pain Scale.

BACKGROUND: Through two studies, we introduce and validate the Empathy for Pain Scale (EPS), which characterizes the phenomenology of empathy for pain, including the vicarious experience of pain when seeing others in pain. METHODS: In study 1, 406 individuals completed the EPS and Interpersonal Reactivity Index (IRI). In the EPS, four painful scenarios (witnessing surgery, patient recovering from surgery, assault and accidental injury) were rated for 12 emotional, empathic and sensory responses. In study 2, 59 participants completed the same questionnaires and then watched and rated videos of sporting injuries. RESULTS: In study 1, we identified three factors of the EPS with principal component analysis, which were validated with confirmatory factor analysis: affective distress; vicarious pain; and empathic concern. The EPS demonstrated good psychometric properties, re-test reliability (n = 105) and concurrent validity. In study 2, we validated the EPS against empathic reactions to the pain of others as displayed in video clips depicting sporting injuries and showed that the scale has unique utility to characterize empathic reactions to pain above general trait empathy measures. Both studies showed that the affective distress and empathic concern subscales of the EPS correlated with measures of cognitive and affective empathy from the IRI, whereas the vicarious pain subscale was only correlated with the personal distress IRI subscale. CONCLUSIONS: The EPS is a psychometrically sound new scale that characterizes empathy for pain and vicarious pain. The EPS offers valuable insight to the phenomenological profile of the affective, empathic and sensory dimensions of empathy for pain.

An examination of the influence of visuomotor associations on interpersonal motor resonance.

The adaptation account of mirror neurons in humans proposes that mirror systems have been selected for in evolution to facilitate social cognition. By contrast, a recent "association" account of mirror neurons in humans argues that mirror systems are not the result of a specific adaptation, but of sensorimotor learning arising from concurrent visual and motor activity. Here, we used transcranial magnetic stimulation (TMS) and electromyography (EMG) to evaluate whether visuomotor associations affect interpersonal motor resonance, a putative measure of mirror system activity. 18 participants underwent two TMS sessions exploring whether visuomotor associations established throughout one׳s lifespan, namely common movements and movements generated from one׳s own perspective, are associated with increased putative mirror system activity. Our results showed no overall difference in interpersonal motor resonance to common versus uncommon actions, or actions presented from an egocentric (self) versus an allocentric (other) perspective. We did, however, observe increased interpersonal motor resonance within the abductor digiti minimi (ADM) muscle in response to allocentric compared to egocentric movements. As the association model predicts stronger mirror system response to actions with stronger visuomotor associations, such as common movements and those presented from an egocentric perspective, our findings provide little evidence to support the association model.

Functional MRI in NPSLE patients reveals increased parietal and frontal brain activation during a working memory task compared with controls.

OBJECTIVES: Anatomical MRI brain scans may not reflect neurological dysfunction in patients with NPSLE. We used blood-oxygen-level-dependent functional MRI (BOLD-fMRI) to investigate working memory function in NPSLE patients. METHODS: Twenty-seven females took part: nine NPSLE patients (mean age 40 yrs; SLEDAI 10.9); nine RA patients and nine healthy controls. Subjects were tested using the n-back paradigm for working memory, where patients indicate when a stimulus matches one presented n trials previously. Functional scans used 3 mm slices x 30, repetition time 2570 ms, echo time 50 ms. Echo planar images were superimposed onto T1w anatomical images (Siemens 1.5 T). Data analysis used Brain Voyager QX Version 1.7. RESULTS: During the memory task, there was activation in areas serving working memory, executive function and attention in all groups. Nine regions of interest were selected for activation during working memory (N-back task vs fixation, P < or = 0.005). In six out of nine regions, there was greater activation in the NPSLE group. This reached significance in three regions: the posterior inferior parietal lobules of both hemispheres [Brodmann area (BA) 7] separately and combined (P = 0.014, 0.016 and 0.004, respectively), and the supplementary motor area (mid-line frontal lobe) (BA32/6; P = 0.032). CONCLUSIONS: NPSLE patients showed greater frontoparietal activation than the other groups during the memory task, suggesting a greater need to recruit extra cortical pathways, possibly to supplement impaired function of standard pathways.

Development of health surveillance in Togo, west Africa.

Since 1988, the Ministry of Health (MOH) of Togo, with technical assistance from CDC, has systematically adapted and strengthened its health information system (HIS) to enable improved monitoring of trends in diseases. The previous system had been hampered by complicated, lengthy reporting forms; incomplete and delayed receipt of reporting forms; absence of mortality reporting; slow, cumbersome manual compilation and analysis methods; and lack of standard case definitions. To simplify the adaptation process, the system was divided into three main activities: data collection, data compilation and analysis, and dissemination of reports and follow-up action. Public health authorities in Togo have built on existing strengths and successfully adapted the HIS to focus on national morbidity and mortality prevention priorities.

Hepatocellular carcinoma with cardiac cirrhosis.

Hepatocellular carcinoma is a recognized complication of hepatic cirrhosis, most commonly associated with alcohol excess, haemochromatosis and chronic hepatitis B infection. Long-standing hepatic venous congestion may cause cirrhosis. A search of the literature has not revealed a case of hepatocellular carcinoma complicating cardiac cirrhosis. A case is described and the association is discussed.

Inhaled verapamil in histamine-induced bronchoconstriction.

Fifteen asthmatic subjects participated in a double-blind trial comparing the protective effects of inhaled verapamil, salbutamol, and saline against inhaled histamine. Inhaling verapamil between four repeated histamine inhalation tests produced no significant protection against histamine-induced bronchoconstriction, while there was significant protection with salbutamol (p less than 0.001). Inhaling verapamil before a single inhalation test produced limited but significant protection (p less than 0.05) compared with a saline control in eight asthmatic subjects. This small protective effect in the two-treatment study of eight asthmatics suggests that either the protective effect of verapamil is variable among subjects or a preceding histamine inhalation test blocks the verapamil effect.