1,777 research outputs found
Role of BacA in Lipopolysaccharide Synthesis, Peptide Transport, and Nodulation by \u3cem\u3eRhizobium\u3c/em\u3e sp. Strain NGR234
BacA of Sinorhizobium meliloti plays an essential role in the establishment of nitrogen-fixing symbioses with Medicago plants, where it is involved in peptide import and in the addition of very-long-chain fatty acids (VLCFA) to lipid A of lipopolysaccharide (LPS). We investigated the role of BacA in Rhizobium species strain NGR234 by mutating the bacA gene. In the NGR234 bacA mutant, peptide import was impaired, but no effect on VLCFA addition was observed. More importantly, the symbiotic ability of the mutant was comparable to that of the wild type for a variety of legume species. Concurrently, an acpXL mutant of NGR234 was created and assayed. In rhizobia, AcpXL is a dedicated acyl carrier protein necessary for the addition of VLCFA to lipid A. LPS extracted from the NGR234 mutant lacked VLCFA, and this mutant was severely impaired in the ability to form functional nodules with the majority of legumes tested. Our work demonstrates the importance of VLCFA in the NGR234-legume symbiosis and also shows that the necessity of BacA for bacteroid differentiation is restricted to specific legume-Rhizobium interactions
Implementation of a Pulsed-Laser Measurement System in the National Transonic Facility
A remotely-adjustable laser transmission and imaging system has been developed for use in a high-pressure, cryogenic wind tunnel. Implementation in the National Transonic Facility has proven the system suitable for velocity and signal lifetime measurements over a range of operating conditions. The measurement system allows for the delivery of high-powered laser pulses through the outer pressure shell and into the test section interior from a mezzanine where the laser is free from environmental disturbances (such as vibrations and excessive condensation) associated with operation of the wind tunnel. Femtosecond laser electronic excitation tagging (FLEET) was utilized to provide freestream velocity measurements, and first results show typical data that may be obtained using the system herein described
Dementia Prevalence Estimates in Sub-Saharan Africa: Comparison of two Diagnostic Criteria.
We have previously reported the prevalence of dementia in older adults living in the rural Hai district of Tanzania according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria. The aim of this study was to compare prevalence rates using the DSM-IV criteria with those obtained using the 10/66 diagnostic criteria, which is specifically designed for use in low- and middle-income countries. In phase I, 1,198 people aged 70 and older were screened for dementia. A stratified sample of 296 was then clinically assessed for dementia according to the DSM-IV criteria. In addition, data were collected according to the protocol of the 10/66 Dementia Research Group, which allowed a separate diagnosis of dementia according to these criteria to be established. The age-standardised prevalence of clinical DSM-IV dementia was 6.4% (95% confidence interval [CI] 4.9-7.9%) and of '10/66 dementia' was 21.6% (95% CI 17.5-25.7%). Education was a significant predictor of '10/66 dementia', but not of DSM-IV dementia. There are large discrepancies in dementia prevalence rates depending on which diagnostic system is used. In rural sub-Saharan Africa, it is not clear whether the association between education and dementia using the 10/66 criteria is a genuine effect or the result of an educational bias within the diagnostic instrument. Despite its possible flaws, the DSM-IV criteria represent an international standard for dementia diagnosis. The 10/66 diagnostic criteria may be more appropriate when identification of early and mild cognitive impairment is required
Interview with Lydia Groves
An interview with Lydia Groves regarding her experiences in a one-room school house.https://scholars.fhsu.edu/ors/1063/thumbnail.jp
Dissociating Stimulus-Set and Response-Set in the Context of Task-Set Switching
The primary aim of the present research was to determine how stimulus-set and response-set components of task-set contribute to switch costs and conflict processing. Three experiments are described wherein participants completed an explicitly cued task-switching procedure. Experiment 1 established that task switches requiring a reconfiguration of both stimulus- and response-set incurred larger residual switch costs than task switches requiring the reconfiguration of stimulus-set alone. Between-task interference was also drastically reduced for response-set conflict compared with stimulus-set conflict. A second experiment replicated these findings and demonstrated that stimulus- and response-conflict have dissociable effects on the decision time and motor time components of total response time. Finally, a third experiment replicated Experiment 2 and demonstrated that the stimulus- and response- components of task switching and conflict processing elicit dissociable neural activity as evidence by event-related brain potentials
Social Competence Treatment after Traumatic Brain Injury: A Multicenter, Randomized, Controlled Trial of Interactive Group Treatment versus Non-Interactive Treatment
Objective
To evaluate the effectiveness of a replicable group treatment program for improving social competence after traumatic brain injury (TBI).
Design
Multicenter randomized controlled trial comparing two methods of conducting a social competency skills program, an interactive group format versus a classroom lecture.
Setting
Community and Veteran rehabilitation centers.
Participants
179 civilian, military, and veteran adults with TBI and social competence difficulties, at least 6 months post-injury.
Experimental Intervention
Thirteen weekly group interactive sessions (1.5 hours) with structured and facilitated group interactions to improve social competence.
Alternative (Control) Intervention
Thirteen traditional classroom sessions using the same curriculum with brief supplemental individual sessions but without structured group interaction.
Primary Outcome Measure
Profile of Pragmatic Impairment in Communication (PPIC), an objective behavioral rating of social communication impairments following TBI.
Secondary Outcomes
LaTrobe Communication Questionnaire (LCQ), Goal Attainment Scale (GAS), Satisfaction with Life Scale (SWLS), Post-Traumatic Stress Disorder Checklist – (PCL-C), Brief Symptom Inventory 18 (BSI-18), Scale of Perceived Social Self Efficacy (PSSE).
Results
Social competence goals (GAS) were achieved and maintained for most participants regardless of treatment method. Significant improvements in the primary outcome (PPIC) and two of the secondary outcomes (LCQ and BSI) were seen immediately post-treatment and at 3 months post-treatment in the AT arm only, however these improvements were not significantly different between the GIST and AT arms. Similar trends were observed for PSSE and PCL-C.
Conclusions
Social competence skills improved for persons with TBI in both treatment conditions. The group interactive format was not found to be a superior method of treatment delivery in this study
Effect of SLM Build Parameters on the Compressive Properties of 304L Stainless Steel
Selective laser melting (SLM) is well suited for the efficient manufacturing of complex structures because of its manufacturing methodology. The optimized process parameters for each alloy has been a cause for debate in recent years. In this study, the hatch angle and build orientation were investigated. 304L stainless steel samples were manufactured using three hatch angles (0◦, 67◦, and 105◦) in three build orientations (x-, y-, and z-direction) and tested in compression. Analysis of variance and Tukey\u27s test were used to evaluate the obtained results. Results showed that the measured compressive yield strength and plastic flow stress varied when the hatch angle and build orientation changed. Samples built in the y-direction exhibited the highest yield strength irrespective of the hatch angle; although, samples manufactured using a hatch angle of 0◦ exhibited the lowest yield strength. Samples manufactured with a hatch angle of 0◦ flowed at the lowest stress at 35% plastic strain. Samples manufactured with hatch angles of 67◦ and 105◦ flowed at statistically the same flow stress at 35% plastic strain. However, samples manufactured with a 67◦ hatch angle deformed non-uniformly. Therefore, it can be concluded that 304L stainless steel parts manufactured using a hatch angle of 105◦ in the y-direction exhibited the best overall compressive behavior
Cortisol is related to acute leukocytosis in maximal but not in hypertrophic dynamic resistance exercise
Introduction. Exercise induces immune changes that are multifactorial and include neuroendocrine factors. Acute resistance exercise is followed by marked increases in adrenaline, cortisol, growth hormone, and other factors that have immunomodulatory effects. The purpose of the present study was to investigate the relationship between leukocytosis and hormone responses to two different resistance exercises, low volume high load (gains in maximal strength, MAX) and high volume medium load (gains in muscle mass, HYP).
Methods. Using a cross-over design twelve healthy men participated in bilateral leg press exercise consisting of 5 sets of 10 RM and 15 sets of 1 RM. The inter-set rest period was 3 minutes for MAX and 2 minutes for HYP. Venous blood samples were taken at baseline, immediately after (P0) and 15 (P15) and 30 (P30) minutes after the exercise. Basic blood count was analyzed using Sysmex KX-21N (TOA Medical Electronics Co., Ltd., Kobe, Japan). Serum cortisol (COR), testosterone (TES), and growth hormone (GH) concentrations were analyzed by an immunometric chemiluminence method (Immunlite R 1000, DPC, Los Angeles, USA)
Results. Both exercises induced significant acute leukocytosis (p\u3c0.001). Leukocytosis was significantly higher after HYP (p\u3c0.01). COR and TES increased significantly after HYP (p\u3c0.01) but not in MAX. GH increased significantly (p\u3c0.05) in both exercises and stayed elevated at P30 in HYP. There was a significant negative correlation between acute leukocytosis and cortisol at P0 in MAX (R=-0.622, p=0.031) but not in HYP r=0.287 (p=0.366). Significant correlations between TES, GH and leukocytes were not observed.
Conclusions. Clearly, manipulation of the rest period and load in resistance exercise alters endocrinal as well as immunological responses. Hypertrophic resistance exercise triggered significantly stronger immunological as well as endocrinal responses. In line with the previous studies (e.g. Kraemer et al. 1996) cortisol did not correlate with leukocytes nor with leukocyte subgroups in HYP. It might be that cortisol acts as an anti-inflammatory agent in MAX, however in HYP leukocytosis appears to be related to additional physiological mechanisms e.g. muscle damage and metabolic demands, which might explain why we did not observe the same in HYP. When considering recovery from resistance exercise the immune system should be monitored in addition to hormones
Stroke risk factors in an incident population in urban and rural Tanzania: a prospective, community-based, case-control study
Background The burden of stroke on health systems in low-income and middle-income countries is increasing.
However, high-quality data for modifi able stroke risk factors in sub-Saharan Africa are scarce, with no communitybased,
case-control studies previously published. We aimed to identify risk factors for stroke in an incident population
from rural and urban Tanzania.
Methods Stroke cases from urban Dar-es-Salaam and the rural Hai district were recruited in a wider study of stroke
incidence between June 15, 2003, and June 15, 2006. We included cases with fi rst-ever and recurrent stroke.
Community-acquired controls recruited from the background census populations of the two study regions were
matched with cases for age and sex and were interviewed and assessed. Data relating to medical and social history
were recorded and blood samples taken.
Findings We included 200 stroke cases (69 from Dar-es-Salaam and 131 from Hai) and 398 controls (138 from Dar-es-
Salaam and 260 from Hai). Risk factors were similar at both sites, with previous cardiac event (odds ratio [OR] 7·39,
95% CI 2·42–22·53; p<0·0001), HIV infection (5·61, 2·41–13·09; p<0·0001), a high ratio of total cholesterol to HDL
cholesterol (4·54, 2·49–8·28; p<0·0001), smoking (2·72, 1·49–4·96; p=0·001), and hypertension (2·14, 1·09–4·17;
p=0·026) identifi ed as signifi cant independent risk factors for stroke. In Hai, additional risk factors of diabetes (4·04,
1·29–12·64) and low HDL cholesterol (9·84, 4·06–23·84) were also signifi cant.
Interpretation We have identifi ed many of the risk factors for stroke already reported for other world regions. HIV
status was an independent risk factor for stroke within an antiretroviral-naive population. Clinicians should be aware
of the increased risk of stroke in people with HIV, even in the absence of antiretroviral treatment
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