Co-activation: its association with weakness and specific neurological pathology

BACKGROUND: Net agonist muscle strength is in part determined by the degree of antagonist co-activation. The level of co-activation might vary in different neurological disorders causing weakness or might vary with agonist strength. AIM: This study investigated whether antagonist co-activation changed a) with the degree of muscle weakness and b) with the nature of the neurological lesion causing weakness. METHODS: Measures of isometric quadriceps and hamstrings strength were obtained. Antagonist (hamstring) co-activation during knee extension was calculated as a ratio of hamstrings over quadriceps activity both during an isometric and during a functional sit to stand (STS) task (using kinematics) in groups of patients with extrapyramidal (n = 15), upper motor neuron (UMN) (n = 12), lower motor neuron (LMN) with (n = 18) or without (n = 12) sensory loss, primary muscle or neuromuscular junction disorder (n = 17) and in healthy matched controls (n = 32). Independent t-tests or Mann Witney U tests were used to compare between the groups. Correlations between variables were also investigated. RESULTS: In healthy subjects mean (SD) co-activation of hamstrings during isometric knee extension was 11.8 (6.2)% and during STS was 20.5 (12.9)%. In patients, co-activation ranged from 7 to 17% during isometric knee extension and 15 to 25% during STS. Only the extrapyramidal group had lower co-activation levels than healthy matched controls (p < 0.05). Agonist isometric muscle strength and co-activation correlated only in muscle disease (r = -0.6, p < 0.05) and during STS in UMN disorders (r = -0.7, p < 0.5). CONCLUSION: It is concluded that antagonist co-activation does not systematically vary with the site of neurological pathology when compared to healthy matched controls or, in most patient groups, with strength. The lower co-activation levels found in the extrapyramidal group require confirmation and further investigation. Co-activation may be relevant to individuals with muscle weakness. Within patient serial studies in the presence of changing muscle strength may help to understand these relationships more clearly

Assessing Biofuel Crop Invasiveness: A Case Study

BACKGROUND: There is widespread interest in biofuel crops as a solution to the world's energy needs, particularly in light of concerns over greenhouse-gas emissions. Despite reservations about their adverse environmental impacts, no attempt has been made to quantify actual, relative or potential invasiveness of terrestrial biofuel crops at an appropriate regional or international scale, and their planting continues to be largely unregulated. METHODOLOGY/PRINCIPAL FINDINGS: Using a widely accepted weed risk assessment system, we analyzed a comprehensive list of regionally suitable biofuel crops to show that seventy percent have a high risk of becoming invasive versus one-quarter of non-biofuel plant species and are two to four times more likely to establish wild populations locally or be invasive in Hawaii or in other locations with a similar climate. CONCLUSIONS/SIGNIFICANCE: Because of climatic and ecological similarities, predictions of biofuel crop invasiveness in Hawaii are applicable to other vulnerable island and subtropical ecosystems worldwide. We demonstrate the utility of an accessible and scientifically proven risk assessment protocol that allows users to predict if introduced species will become invasive in their region of interest. Other evidence supports the contention that propagule pressure created by extensive plantings will exacerbate invasions, a scenario expected with large-scale biofuel crop cultivation. Proactive measures, such as risk assessments, should be employed to predict invasion risks, which could then be mitigated via implementation of appropriate planting policies and adoption of the "polluter-pays" principle

The vaccination of 35,000 dogs in 20 working days using combined static point and door-to-door methods in Blantyre, Malawi

An estimated 60,000 people die of rabies annually. The vast majority of cases of human rabies develop following a bite from an infected dog. Rabies can be controlled in both human and canine populations through widespread vaccination of dogs. Rabies is particularly problematic in Malawi, costing the country an estimated 13 million USD and 484 human deaths annually, with an increasing paediatric incidence in Blantyre City. Consequently, the aim of this study was to vaccinate a minimum of 75% of all the dogs within Blantyre city during a one month period. Blantyre's 25 administrative wards were divided into 204 working zones. For initial planning, a mean human:dog ratio from the literature enabled estimation of dog population size and dog surveys were then performed in 29 working zones in order to assess dog distribution by land type. Vaccination was conducted at static point stations at weekends, at a total of 44 sites, with each operating for an average of 1.3 days. On Monday to Wednesday, door-to-door vaccination sessions were undertaken in the areas surrounding the preceding static point stations. 23,442 dogs were vaccinated at static point stations and 11,774 dogs were vaccinated during door-to-door vaccinations. At the end of the 20 day vaccination programme, an assessment of vaccination coverage through door-to-door surveys found that of 10,919 dogs observed, 8,661 were vaccinated resulting in a vaccination coverage of 79.3% (95%CI 78.6-80.1%). The estimated human:dog ratio for Blantyre city was 18.1:1. Mobile technology facilitated the collection of data as well as efficient direction and coordination of vaccination teams in near real time. This study demonstrates the feasibility of vaccinating large numbers of dogs at a high vaccination coverage, over a short time period in a large African city

Status of management and control efforts for the invasive alien tree Miconia calvescens DC. (Melastomataceae) in Hana, East Maui

Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.This report is a conglomeration of the research and monitoring that has been conducted in the area of the Hana Miconia calvescens population since this weed was addressed as a biological threat to native Hawaiian ecosystems in 1991. Despite the amount of time that was spent in the area, and the abundance of useful information that was gathered during the course of the past nine years, many important questions concerning the biology and ecology of M. calvescens, particularly as they apply to the Hawaiian Islands, have yet to be answered

Assessing biofuel crop invasiveness: a case study. PLoS One 4:e5261

Abstract Background: There is widespread interest in biofuel crops as a solution to the world&apos;s energy needs, particularly in light of concerns over greenhouse-gas emissions. Despite reservations about their adverse environmental impacts, no attempt has been made to quantify actual, relative or potential invasiveness of terrestrial biofuel crops at an appropriate regional or international scale, and their planting continues to be largely unregulated

Notes on Status and Ecology of the Endangered Hawaiian Annual Awiwi, Centaurium sebaeoides (Gentianaceae)

The annual, endemic, coastal herb Centaurium sebaeoides is the only native Hawaiian species in the gentian family. The U.S. Fish and Wildlife Service listed it as Endangered under the Endangered Species Act on 29 October 1991. Before surveys reported here, the total population of this species statewide was estimated at 80-110 individuals in eight populations. During counts made in April and May 1997, following ample winter rains, 12 populations of C. sebaeoides with a total of 6300-6600 plants were noted on five islands (Kaua'i, O'ahu, Lana'i, Moloka'i, and Maui). Five populations were mapped with a global positioning system and counted; in the remaining seven populations, the numbers of individuals were estimated. More recent surveys in 1998-1999 estimated a total of only 60-80 individuals at all sites. Such dramatic population fluctuations are believed to be related to the sporadic occurrence of winter rains. Threats that further contribute to the rarity of the species include (1) displacement and overtopping by salt-tolerant nonnative woody species, especially Casuarina spp., (2) trampling and erosion of habitat by ungulates, and (3) damage caused by off-road vehicles

List of biofuels (n = 40) and introduced species (n = 40) in the Hawaiian Islands (HI) analyzed in this study, with associated Weed Risk Assessment (WRA) scores, naturalization (Nat) or invasive (Inv) status, biofuel use and risk category (H = High, L = Low, E = Evaluate^*, NA = Not Assessable).

*<p>Risk designation for WRA scores of 1–6 follows use of a secondary screening developed by Daehler et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005261#pone.0005261-Daehler1" target="_blank">[14]</a>.</p

The number (percentages) of biofuel crops (n = 40) and a random selection of introduced (n = 40) species with their invasiveness status in this study; to calculate percentages for biofuels naturalized and invasive in Hawaii we use biofuel species present in Hawaii for the denominator (i.e., 38).

**<p>Binomial proportion tests significant at the 0.001 level.</p

Numbers (percentages) of species falling into the WRA risk categories within a group of species proposed as biofuels and a random selection of introduced species in Hawaii.

<p>Numbers (percentages) of species falling into the WRA risk categories within a group of species proposed as biofuels and a random selection of introduced species in Hawaii.</p