Perceived exertion as a tool to self-regulate exercise in individuals with tetraplegia

The purpose of this investigation was to examine the use of subjective rating of perceived exertion (RPE) as a tool to self-regulate the intensity of wheelchair propulsive exercise in individuals with tetraplegia. Eight motor complete tetraplegic (C5/6 and below; ASIA Impairment Scale = A) participants completed a submaximal incremental exercise test followed by a graded exercise test to exhaustion to determine peak oxygen uptake ( $ \dot{V}O_{{ 2 {\text{peak}}}} $ ) on a wheelchair ergometer. On a separate day, a 20-min exercise bout was completed at an individualised imposed power output (PO) equating to 70 % of $ \dot{V}O_{{ 2 {\text{peak}}}} $ . On a third occasion, participants were instructed to maintain a workload equivalent to the average RPE for the 20-min imposed condition. $ \dot{V}O_{2} $ , heart rate (HR) and PO were measured at 1-min intervals and blood lactate concentration [BLa^?] was measured at 0, 10 and 20 min. No differences (P > 0.17) were found between mean $ \dot{V}O_{2} $ , %  $ \dot{V}O_{{ 2 {\text{peak}}}} $ , HR, % HR_peak, [BLa^?], velocity or PO between the imposed and RPE-regulated trials. No significant (P > 0.05) time-by-trial interaction was present for $ \dot{V}O_{2} $ data. A significant interaction (P < 0.001) for the PO data represented a trend for an increase in PO from 10 min to the end of exercise during the RPE-regulated condition. However, post hoc analysis revealed none of the differences in PO across time were significant (P > 0.05). In conclusion, these findings suggest that RPE can be an effective tool for self-regulating 20 min of wheelchair propulsion in a group of trained participants with tetraplegia who are experienced in wheelchair propulsion.     

Ex vivo treatment of proliferating human cord blood stem cells with stroma-derived factor-1 enhances their ability to engraft NOD/SCID mice

Ex vivo proliferation of hematopoietic stem cells (HSCs) is important for cellular and gene therapy but is limited by the observation that HSCs do not engraft as they transit S/G(2)/M. Recently identified candidate inhibitors of human HSC cycling are transforming growth factor-beta(1) (TGF-beta(1)) and stroma-derived factor-1 (SDF-1). To determine the ability of these factors to alter the transplantability of human HSCs proliferating in vitro, lin(-) cord blood cells were first cultured for 96 hours in serum-free medium containing Flt3 ligand, Steel factor, interleukin-3, interleukin-6, and granulocyte colony-stimulating factor. These cells were then transferred to medium containing Steel factor and thrombopoietin with or without SDF-1 and/or TGF-beta(1) for 48 hours. Exposure to SDF-1 but not TGF-beta(1) significantly increased (> 2-fold) the recovery of HSCs able to repopulate nonobese diabetic/severe combined immunodeficiency mice. These results suggest new strategies for improving the engraftment activity of HSCs stimulated to proliferate ex vivo.     

Physical inactivity in patients with rheumatoid arthritis: data from twenty-one countries in a cross-sectional, international study

OBJECTIVE: Regular physical activity is associated with decreased morbidity and mortality. Traditionally, patients with rheumatoid arthritis (RA) have been advised to limit physical exercise. We studied the prevalence of physical activity and associations with demographic and disease-related variables in patients with RA from 21 countries. METHODS: The Questionnaires in Standard Monitoring of Patients with Rheumatoid Arthritis (QUEST-RA) is a cross-sectional study that includes a self-report questionnaire and clinical assessment of nonselected consecutive outpatients with RA who are receiving usual clinical care. Frequency of physical exercise (>or=30 minutes with at least some shortness of breath, sweating) is queried with 4 response options: >or=3 times weekly, 1-2 times weekly, 1-2 times monthly, and no exercise. RESULTS: Between January 2005 and April 2007, a total of 5,235 patients from 58 sites in 21 countries were enrolled in QUEST-RA: 79% were women, >90% were white, mean age was 57 years, and mean disease duration was 11.6 years. Only 13.8% of all patients reported physical exercise>or=3 times weekly. The majority of the patients were physically inactive with no regular weekly exercise: >80% in 7 countries, 60-80% in 12 countries, and 45% and 29% in 2 countries, respectively. Physical inactivity was associated with female sex, older age, lower education, obesity, comorbidity, low functional capacity, and higher levels of disease activity, pain, and fatigue. CONCLUSION: In many countries, a low proportion of patients with RA exercise. These data may alert rheumatologists to motivate their patients to increase physical activity levels.     

Acute effects and long-term outcome of pulmonary vein isolation in combination with electrogram-guided substrate ablation for persistent atrial fibrillation

Complex fractionated atrial electrographic (CFAE) catheter ablation is a new approach for the treatment of atrial fibrillation (AF). It is unclear if acute results of this approach correspond to long-term outcome. The purpose of this study was to prospectively assess acute and long-term successes of an ablation approach combining pulmonary vein isolation (PVI) and ablation of CFAE areas for treatment of persistent AF. PVI and ablation of CFAE areas were performed in 35 patients with persistent AF (30 men, 57+/-9 years of age). At the end of the ablation procedure AF had terminated in 23 of 35 patients (66%) by conversion to sinus rhythm (8 of 23 patients, 35%) or organization to atrial tachycardia (15 of 23 patients, 65%). AF persisted in 12 of 35 patients (34%). At the end of the follow-up period (19+/-12 months), sinus rhythm was present in 26 of 35 patients (74%), including 9 patients with a repeat procedure. This group of 26 patients consisted of 7 of 8 patients (88%) with acute sinus rhythm after the first ablation, 11 of 15 patients (73%) with organization, and 8 of 12 patients (66%) with ongoing AF (p=0.32). In conclusion, a combined approach of PVI and CFAE ablation in persistent AF leads to acute AF termination in 66% and long-term maintenance of sinus rhythm in 74% of cases. However, long-term outcome was not predictable by acute results of the ablation procedure.     

Left ventricular assist device support reverses altered cardiac expression and function of natriuretic peptides and receptors in end-stage heart failure

OBJECTIVE: Atrial (ANP) and B-type natriuretics peptides (BNP) via their guanylyl cyclase-A (GC-A) receptor not only regulate arterial blood pressure and volume but also exert local antihypertrophic, antifibrotic and lusitropic effects in the heart. To elucidate whether cardiac hypertrophy/insufficiency and reversal is associated with changes in the local responsiveness to NPs, we compared the mRNA expression of ANP, BNP and receptors and the responsiveness of GC-A to ANP in left ventricular tissue obtained from 10 patients with congestive heart failure (CHF) before and after hemodynamic unloading by left ventricular assist device (LVAD) support. METHODS AND RESULTS: Quantitative "real time" RT-PCR demonstrated that the mRNA expression levels of ANP, BNP and the NP-metabolizing NPR-C receptor were both markedly increased in human failing hearts. GC-A mRNA expression levels were not different from nonfailing hearts, but cGMP production by GC-A in response to ANP was nearly abolished. Reversal of cardiomyocyte hypertrophy during LVAD support was accompanied by normalization of ANP, BNP and NPR-C mRNA levels and a significant recovery of GC-A responsiveness to ANP. CONCLUSION: In CHF patients, increased local clearance by NPR-C receptors and diminished responsiveness of cardiac GC-A might impair the local antihypertrophic effects of natriuretic peptides and contribute to the progression of cardiac hypertrophy and insufficiency. Reverse remodeling during LVAD support reverses these changes and can thereby recuperate the local protective effects of ANP and BNP.     

Rapid natural scene categorization in the near absence of attention

What can we see when we do not pay attention? It is well known that we can be "blind" even to major aspects of natural scenes when we attend elsewhere. The only tasks that do not need attention appear to be carried out in the early stages of the visual system. Contrary to this common belief, we report that subjects can rapidly detect animals or vehicles in briefly presented novel natural scenes while simultaneously performing another attentionally demanding task. By comparison, they are unable to discriminate large T's from L's, or bisected two-color disks from their mirror images under the same conditions. We conclude that some visual tasks associated with "high-level" cortical areas may proceed in the near absence of attention.