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排序方式: 共有288条查询结果,搜索用时 31 毫秒
141.
142.
Bart Visser Michiel P de Looze DirkJan H E J Veeger Marjolein Douwes Liesbeth Groenesteijn Elsbeth de Korte Jaap H van Die?n 《Journal of electromyography and kinesiology》2003,13(2):149-157
High precision demands in manual tasks can be expected to cause more selective use of a part of the muscular synergy involved. To test this expectation, load sharing of the index finger and middle finger was investigated during a pinching task. Myoelectric activation of lower arm and neck-shoulder muscles was measured to see if overall level of effort was affected by precision demands. Ten healthy female subjects performed pinching tasks with three levels of force and three levels of precision demands. The force level did not significantly affect the relative contribution of the index and middle finger to the force. Higher precision demands, however, led to higher contribution of the index finger to the pinch force. Consequently, a more selective load of the forearm and hand occurs during tasks with high precision demands. The variability of the force contribution of the fingers increased during the task. No effects of precision demand on the activation of forearm and neck-shoulder muscles were found. Force level did affect the EMG parameters of several muscles. The effects were most apparent in the muscles responsible for the pinch force, the forearm muscles. Activation of these muscles was higher at higher force levels. In the trapezius muscle at the dominant side EMG amplitudes were lower at the high pinch force compared to the low force and median force conditions. 相似文献
143.
AC Martin IA Laing G Zhang S Brennan K Winfield PD Sly SM Stick J Goldblatt PN LeSouef 《Respiratory research》2005,6(1):1-4
Early acquisition of Pseudomonas aeruginosa is associated with a poorer prognosis in patients with cystic fibrosis. We investigated whether polymorphisms in CD14, the lipopolysaccharide receptor, increase the risk of early infection. Forty-five children with cystic fibrosis were investigated with annual bronchoalveolar lavage (BAL) and plasma sCD14 levels. Plasma sCD14 levels were significantly lower in children from whom P.aeruginosa was subsequently isolated (492.75 μg/ml vs. 1339.43 μg/ml, p = 0.018). Those with the CD14 -159CC genotype had a significantly increased risk of early infection with P.aeruginosa suggesting that CD14 C-159T plays a role in determining the risk of early infection with P.aeruginosa. 相似文献
144.
The current study was conducted to investigate the effects of dietary zinc oxide (ZnO) on the antioxidant capacity, small intestine development, and jejunal gene expression in weaned piglets. Ninety-six 21-day-old piglets were randomly assigned to three dietary treatments. Each treatment had eight replicates with four piglets per replicate. The piglets were fed either control diet (control) or control diet supplemented with in-feed antibiotics (300 mg/kg chlortetracycline and 60 mg/kg colistin sulfate) or pharmacological doses of ZnO (3000 mg/kg). The experiment lasted 4 weeks. Blood samples were collected at days 14 and 28, while intestinal samples were harvested at day 28 of the experiment. Dietary high doses of ZnO supplementation significantly increased the body weight (BW) at day 14 and average daily gain (ADG) of days 1 to 14 in weaned piglets, when compared to control group (P < 0.05). The incidence of diarrhea of piglets fed ZnO-supplemented diets, at either days 1 to 14, days 14 to 28, or the overall experimental period, was significantly decreased in comparison with those in other groups (P < 0.05). Supplementation with ZnO increased the villus height of the duodenum and ileum in weaned piglets and decreased the crypt depth of the duodenum, when compared to the other groups (P < 0.05). Dietary ZnO supplementation decreased the malondialdehyde (MDA) concentration at either day 14 or day 28, but increased total superoxide dismutase (T-SOD) at day 14, when compared to that in the control (P < 0.05). ZnO supplementation upregulated the messenger RNA (mRNA) expression of zonula occludens-1 (ZO-1) and occludin in the jejunum mucosa of weaned piglets, compared to those in the control (P < 0.05). The pro-inflammatory cytokine interleukin-lβ (IL-1β) mRNA expression in the jejunum mucosa was downregulated in the ZnO-supplemented group, compared with the control (P < 0.05). Both in-feed antibiotics and ZnO supplementation decreased the mRNA expression of interferon-γ (IFN-γ), but increased the mRNA expression of transforming growth factor-β (TGF-β), in the jejunum mucosa of piglets, when compared to those in the control (P < 0.05). In summary, supplemental ZnO was effective on the prevention of post-weaning diarrhea (PWD) in weaned piglets and showed comparative growth-promoting effect on in-feed antibiotics, probably by the mechanism of improvement of the antioxidant capacity, restoration of intestinal barrier function and development, and modulation of immune functions. 相似文献
145.
Molecular phylogenetics reveal multiple tertiary vicariance origins of the African rain forest trees
Background
Tropical rain forests are the most diverse terrestrial ecosystems on the planet. How this diversity evolved remains largely unexplained. In Africa, rain forests are situated in two geographically isolated regions: the West-Central Guineo-Congolian region and the coastal and montane regions of East Africa. These regions have strong floristic affinities with each other, suggesting a former connection via an Eocene pan-African rain forest. High levels of endemism observed in both regions have been hypothesized to be the result of either 1) a single break-up followed by a long isolation or 2) multiple fragmentation and reconnection since the Oligocene. To test these hypotheses the evolutionary history of endemic taxa within a rain forest restricted African lineage of the plant family Annonaceae was studied. Molecular phylogenies and divergence dates were estimated using a Bayesian relaxed uncorrelated molecular clock assumption accounting for both calibration and phylogenetic uncertainties. 相似文献146.
Besselsen DG Myers EL Franklin CL Korte SW Wagner AM Henderson KS Weigler BJ 《Comparative medicine》2008,58(2):140-144
Intermittent serodetection of mouse parvovirus (MPV) infections in animal facilities occurs frequently when soiled bedding sentinel mouse monitoring systems are used. We evaluated induction of seroconversion in naïve single-caged weanling ICR mice (n = 10 per group) maintained on 5-fold serially diluted contaminated bedding obtained from SCID mice persistently shedding MPV1e. Soiled bedding from the infected SCID mice was collected, diluted, and redistributed weekly to cages housing ICR mice to represent chronic exposure to MPV at varying prevalence in a research colony. Sera was collected every other week for 12 wk and evaluated for reactivity to MPV nonstructural and capsid antigens by multiplex fluorescent immunoassay. Mice were euthanized after seroconversion, and DNA extracted from lymph node and spleen was evaluated by quantitative PCR. Cumulative incidence of MPV infection for each of the 7 soiled bedding dilution groups (range, 1:5 to 1:78125 [v/v]) was 100%, 100%, 90%, 20%, 70%, 60%, and 20%, respectively. Most seropositive mice (78%) converted within the first 2 to 3 wk of soiled bedding exposure, correlating to viral exposure when mice were 4 to 7 wk of age. Viral DNA was detected in lymphoid tissues collected from all mice that were seropositive to VP2 capsid antigen, whereas viral DNA was not detected in lymphoid tissue of seronegative mice. These data indicate seroconversion occurs consistently in young mice exposed to high doses of virus equivalent to fecal MPV loads observed in acutely infected mice, whereas seroconversion is inconsistent in mice chronically exposed to lower doses of virus.Abbreviations: mfi, median fluorescent intensity; MFI, multiplex fluorescent immunoassay; MPV, mouse parvovirus; NS1, nonstructural protein 1; qPCR, quantitative PCR; SCID, severe combined immunodeficiency; VP2, viral capsid protein 2Mouse parvovirus (MPV) is among the most prevalent infectious agents detected in contemporary laboratory mouse colonies2,7,10 and can have deleterious effects on research because of in vitro and in vivo immunomodulatory effects, tumor suppression, and contamination of cell cultures and tissues originating from mice.11-13 The potential for MPV transmission among mice in research facilities is enhanced by its environmental stability,6 potential to induce persistent infection in mice,8 and difficult eradication from infected laboratory mouse colonies. Despite the availability of highly sensitive and specific diagnostic assays,9,14,15 detection of MPV infections in contemporary laboratory mouse colonies remains problematic, with intermittent detection even under conditions of enzootic colony infections. The widespread use of sentinel mice exposed to soiled bedding as the primary detection system, a relatively short period of viral transmission postinfection in immunocompetent mice, and a fairly high viral dose required to induce productive infection are considered key factors that result in intermittent detection of MPV contamination in mouse colonies. As a result, MPV infections present important and costly challenges to contemporary laboratory animal research facilities.Several studies have investigated the horizontal transmission of MPV to sentinel mice. Experimentally infected SENCAR mice transmitted MPV1a to naïve sentinels both by direct contact and soiled bedding exposure, predominantly during the first 3 wk after inoculation.17 Similarly, experimentally infected Swiss Webster mice transmitted MPV1d within 2 wk to sentinels by direct contact or through various amounts of soiled bedding.18 Interestingly, transmission to sentinel mice appeared to be enhanced in mice maintained in individually ventilated caging as compared with static microisolation caging in the cited study. Naturally infected BALB/c mice when 1 mo old, but not when 2, 3, and 6 mo old, transmitted MPV to direct contact sentinels.16 Recent studies completed in our laboratory1 indicate that C.B-17/Icr-Prkdcscid mice inoculated with MPV1e as neonates persistently shed high levels of virus in their feces over several months. Undiluted contaminated bedding collected at any time point during this period consistently transmitted MPV1e to weanling C3H sentinel mice exposed for 2 wk. Similarly inoculated neonatal BALB/c mice shed high levels of virus, with transmission to sentinels, for only 2 wk after inoculation.1 In all of these reports, the period of exposure of sentinel mice to soiled bedding was limited (2 wk or less), with no repeated exposure opportunities, as might be expected under field conditions with an infected colony. In the present study, we simulated a typical sentinel monitoring program and determined whether chronic exposure to various concentrations of MPV1-contaminated bedding, reflective of a broad range of disease prevalence scenarios within any given affected room, can induce seroconversion in sentinel mice. 相似文献
147.
Markus Schmidt Wei Wei Anan Polthanee Nguyen Thanh Lam Sophal Chuong Li-juan Qiu Poramate Banterng Pham Thi Dung Stefan Glaser Ralph Gretzmacher Veronika Hager Edwin de Korte Ying-hui Li Nguyen The Phuong Sophoanrith Ro Zeng-yan Zhang Hai-fei Zhou 《Biodiversity and Conservation》2008,17(7):1645-1666
Neglected and Underutilized Crop Species (NUS) are grown primarily by traditional farmers in developing countries. They were
once more widely grown but are today falling into disuse for a variety of agronomic, genetic, economic and cultural factors.
While these crops continue to be maintained by socio-cultural preferences and use practices, most of them remain inadequately
characterized and neglected by research and conservation. The aim of our work was to improve the agricultural portfolio by
identifying promising neglected and underutilised species in China, Cambodia, Northeastern Thailand and Northern Vietnam.
We began with preparing a “Masterlist” containing 260 species, based on farmer interviews and literature review. After an
initial pre-selection we identified 17 NUS for China, 13 for Cambodia, 12 for Thailand, and 22 for Vietnam as of highest priority.
These NUS then underwent a multi-criteria and trans-disciplinary assessment involving 511 stakeholders such as scientists,
farmers, NGOs and policy makers. Based on the assessment we identified the most promising NUS for each country. We also identified
some limitations for the promotion of so-called priority NUS regarding to some substancial disagreement between the involved
stakeholders. In China and Cambodia, for example, farmers judged the potential of NUS significantly lower than other stakeholders,
and in Vietnam scientists and policy makers had substantially different opinions on NUS compared to farmers. Addressing these
ambiguous views will be highly relevant to the develoment of an improved agricultural portfolio.
相似文献
Markus SchmidtEmail: Email: |
148.
During the first weeks of life, preterm neonates show fewer circadian rhythms in their physiological parameters than full-term neonates. To determine whether preterm neonates differ in their temporal adaptation to the daynight cycle from full-term neonates at the early age of 1 week, we compared activity-rest behavior of both groups. Activity-rest behavior of 10 neurologically healthy preterm neonates (born in 34th to 36th week of gestation) and 10 neurologically healthy full-term neonates (born in 37th to 42nd week of gestation) was monitored longitudinally for 8 successive days in the first 2 weeks of life. Actigraphy was used to register and display time patterns of activity and rest in neonates by using small actometers, which resemble a wristwatch. Nursing/feeding was recorded using the actometer's integrated event marker button. Recordings for preterm neonates were conducted in the hospital; recordings for full-term neonates were carried out in the hospital and in their homes. In addition to the actigraphic recordings, a standardized diary was kept regularly. To assess periodic characteristics, frequency components of activity-rest behavior were analyzed using fast Fourier transformation (FFT). Amounts of daily sleep time, nightly sleep time, and sleep time during 24h were compared. Nursing/feeding epochs were also analyzed for 5 preterm and 5 full-term neonates to compare their food intake behavior. The majority of preterm neonates showed a multitude of ultradian frequencies in their spectra. In contrast, several full-term neonates showed a distinct circadian frequency. In preterm neonates, average nightly sleep and average daily sleep of all recorded days were very similar, but after the fourth day of life, only average nightly sleep increased. In full-term neonates, average nightly and daily sleep time of all recorded days differed by about 1h. Average sleep time during 24h for preterm and full-term neonates was similar. Preterm neonates showed longer intervals between events of food intake than full-term neonates. The circadian peaks in the frequency spectra of full-term neonates may indicate the initial adaptation in the first week of life to a 24h day. This is in agreement with our results concerning the different durations of nightly and daily sleep. The increase in nightly sleep time of preterm neonates may be attributed to the progressing adaptation to a circadian activity- rest pattern. (Chronobiology International, 18(4), 697-708, 2001) 相似文献
149.
The tandemly arranged MS4 repeat with monomeric units of 4.1 kb is species-specifically distributed in heterochromatin of sex chromosomes of four common vole species of genus Microtus, group arvalis [1, 2]. In this work, we studied the genomic organization of the MS4 homolog in euchromatin of the X chromosome of M. arvalis. It has been shown by analyzing the phage genomic clones that one MS4 copy makes a part of a monomeric unit exceeding 8.5 kb that also includes a new MS7 repeat and, possibly, LINE fragments. MS7 is located together with MS4 in heterochromatin of common vole sex chromosomes, but in a substantially lesser amount. Probably, as a result of an evolutionary transition of an original repeat from euchromatin of the X chromosome to heterochromatin of the Y chromosome, MS4 underwent multiple amplification, and MS7 spread throughout heterochromatin, being surrounded by the MS4 tandem arrays. 相似文献
150.
Fredriksson-Ahomaa M Niskanen T Bucher M Korte T Stolle A Korkeala H 《Systematic and applied microbiology》2003,26(1):132-137
The distribution of different genotypes of Y. enterocolitica 4:O3 strains recovered from pig tonsils in Southern Germany and Finland in 1999-2000 was investigated. A total of 96 and 207 Y. enterococolitica 4:O3 isolates recovered from 47 and 66 tonsils of finishing pigs in Germany and Finland, respectively, were characterised with PFGE using NotI enzyme. In all, 39 different NotI profiles were obtained, only one of which, NB1, was found in both Germany and Finland. All strains were further characterised with ApaI and XhoI enzymes. When the 54 German and 74 Finnish strains were characterised with all three enzymes, 51 genotypes were obtained. The 23 genotypes found in German strains differed from the 28 found in Finnish strains. These results indicate that Y. enterocolitica 4:O3 genotypes have a differential geographical distribution and thus can be used in epidemiological studies. 相似文献