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Peak Activity (peak + activity)
Selected AbstractsInhibition of the initial wave of NF-,B activity in rat muscle reduces ischemia/reperfusion injuryMUSCLE AND NERVE, Issue 4 2001Sean T. Lille MD Abstract Nuclear factor kappaB (NF-,B) is thought to play an important role in the expression of genes expressed in response to ischemia/reperfusion (I/R) injury. In this report, the activation of NF-,B in rat skeletal muscle during reperfusion following a 4-h ischemic period was studied. NF-,B activation displayed a biphasic pattern, showing peak activities from 30 min to 3 h postperfusion and 6 h to 16 h postperfusion, with a decline to baseline binding activity levels between 3 h and 6 h. Inhibition of NF-,B activation was investigated using proline dithiocarbamate (Pro-DTC). NF-,B binding activity during reperfusion was significantly reduced by intravenous administration of Pro-DTC. Additionally, Pro-DTC resulted in decreased muscle edema and neutrophil activity, with an increased percentage of muscle survival compared with vehicle controls. These results demonstrate that NF-,B is activated during reperfusion in a biphasic manner and that the regulation of the initial phase of NF-,B activation affords physiological protection against a severe ischemic stress. Selective inhibition of NF-,B during early reperfusion may therefore be a therapeutic intervention for I/R injury. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 534,541, 2001 [source] Kinetic analysis of hyaluronidase activity using a bioactive MRI contrast agentCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2006Liora Shiftan Abstract One of the attractions of molecular imaging using ,smart' bioactive contrast agents is the ability to provide non-invasive data on the spatial and temporal changes in the distribution and expression patterns of specific enzymes. The tools developed for that aim could potentially also be developed for functional imaging of enzyme activity itself, through quantitative analysis of the rapid dynamics of enzymatic conversion of these contrast agents. High molecular weight hyaluronan, the natural substrate of hyaluronidase, is a major antiangiogenic constituent of the extracellular matrix. Degradation by hyaluronidase yields low molecular weight fragments, which are proangiogenic. A novel contrast material, HA-GdDTPA-beads, was designed to provide a substrate analog of hyaluronidase in which relaxivity changes are induced by enzymatic degradation. We show here a first-order kinetic analysis of the time-dependent increase in R2 as a result of hyaluronidase activity. The changes in R2 and the measured relaxivity of intact HA-GdDTPA-beads (r2B) and HA-GdDTPA fragments (r2D) were utilized for derivation of the temporal drop in concentration of GdDTPA in HA-GdDTPA-beads as the consequence of the release of HA-GdDTPA fragments. The rate of dissociation of HA-GdDTPA from the beads showed typical bell-shaped temperature dependence between 7 and 36 °C with peak activity at 25 °C. The tools developed here for quantitative dynamic analysis of hyaluronidase activity by MRI would allow the use of activation of HA-GdDTPA-beads for the determination of the role of hyaluronidase in altering the angiogenic microenvironment of tumor micro metastases. Copyright © 2006 John Wiley & Sons, Ltd. [source] Role of GABAA inhibition in modulation of pyramidal tract neuron activity during postural correctionsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007Zinaida A. Tamarova Abstract In a previous study we demonstrated that the activity of pyramidal tract neurons (PTNs) of the motor cortex is modulated in relation to postural corrections evoked by periodical tilts of the animal. The modulation included an increase in activity in one phase of the tilt cycle and a decrease in the other phase. It is known that the motor cortex contains a large population of inhibitory GABAergic neurons. How do these neurons participate in periodic modulation of PTNs? The goal of this study was to investigate the role of GABAA inhibitory neurons of the motor cortex in the modulation of postural-related PTN activity. Using extracellular electrodes with attached micropipettes, we recorded the activity of PTNs in cats maintaining balance on a tilting platform both before and after iontophoretic application of the GABAA receptor antagonists gabazine or bicuculline. The tilt-related activity of 93% of PTNs was affected by GABAA receptor antagonists. In 88% of cells, peak activity increased by 75 ± 50% (mean ± SD). In contrast, the trough activity changed by a much smaller value and almost as many neurons showed a decrease as showed an increase. In 73% of the neurons, the phase position of the peak activity did not change or changed by no more than 0.1 of a cycle. We conclude that the GABAergic system of the motor cortex reduces the posture-related responses of PTNs but has little role in determining their response timing. [source] Fibre-type composition of rabbit jaw muscles is related to their daily activityEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2005T. van Wessel Abstract Skeletal muscles contain a mixture of fibres with different contractile properties, such as maximum force, contraction velocity and fatigability. Muscles adapt to altered functional demands, for example, by changing their fibre-type composition. This fibre-type composition can be changed by the frequency, duration and presumably the intensity of activation. The aim of this study was to analyse the relationship between the spontaneous daily muscle activation and fibre-type composition in rabbit jaw muscles. Using radio-telemetry combined with electromyography, the daily activity of five jaw muscles was characterized in terms of the total duration of muscle activity (duty time) and the number of activity bursts. Fibre-type composition of the muscles was classified by analysing the myosin heavy chain content of the fibres. The amount of slow-type fibres was positively correlated to the duty time and the number of bursts only for activations exceeding 20,30% of the maximum activity per day. Furthermore, cross-sectional areas of the slow-type fibres were positively correlated to the duty time for activations exceeding 30% of the maximum activity. The present data indicate that the amount of activation above a threshold (> 30% peak activity) is important for determining the fibre-type composition and cross-sectional area of slow-type fibres of a muscle. Activation above this threshold occurred only around 2% of the time in the jaw muscles, suggesting that contractile properties of muscle fibres are maintained by a relatively small number of powerful contractions per day. [source] Daily jaw muscle activity in freely moving rats measured with radio-telemetryEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2007Nobuhiko Kawai The jaw muscle activity of rats has been investigated for specific tasks. However, the daily jaw muscle use remains unclear. The purpose of the present study was to examine daily jaw muscle activity, and its variability over time, in the rat (n = 12) by the use of radio-telemetry. A telemetric device was implanted for the continuous recording of masseter muscle and digastric muscle activity. Daily muscle use was characterized by calculating the total time that each muscle was active (duty time), the number of bursts, and the average length of bursts. All parameters were estimated for activities exceeding various levels (5,90%) of the day's peak activity. Daily muscle use remained constant for 4 wk. At the low-activity level, the duty time and burst number of the digastric muscle were significantly (P < 0.01) higher than those of the masseter muscle, whereas the opposite was true at the high-activity level (P < 0.05). No significant intermuscular correlation was observed between the number of bursts of the masseter and digastric muscles, but the interindividual variation of both muscles changed, depending on the level of activation. These findings suggest that the masseter muscle and the digastric muscle show a differential active pattern, depending on the activity level. [source] Influenza-associated hospitalization in urban Thai childrenINFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 5-6 2007Piyarat Suntarattiwong Background, Studies in North America and Europe have shown that young children are at increased risk of serious complications and hospitalization from influenza infection. In Thailand, however, influenza is commonly considered a mild infection that rarely requires hospitalization. An improved understanding of the burden of serious complications from influenza infection in young children is needed to inform clinical treatment and vaccination guidelines. Methods, We conducted a prospective study of children 0,5 years of age with lower respiratory tract infection or influenza-like illness admitted to a pediatric tertiary-care hospital in Bangkok, Thailand during July 2004 to July 2005. All respiratory specimens were tested for influenza using a rapid antigen test and tissue cell culture. Results, Thirty-nine of 456 (8.6%) hospitalized children had culture-positive influenza. Eighty percent of hospitalized influenza patients had no underlying chronic illnesses. Nineteen (49%) influenza patients required hospital stays of 5 days or more and two patients required mechanical ventilation. Influenza activity demonstrated bimodal seasonal variation with peak activity from August to October and January to April. Cough was present in 38 (97%) cases and fever >38.5°C was significantly associated with influenza. Conclusion, Influenza is an important cause of hospitalization in children <5 years of age in Thailand. Children <5 years should be considered as a target group when establishing clinical guidelines for antiviral treatment and influenza vaccination. [source] Circadian Activity Rhythms and Mortality: The Study of Osteoporotic FracturesJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2 2010Gregory J. Tranah PhD OBJECTIVES: To determine whether circadian activity rhythms are associated with mortality in community-dwelling older women. DESIGN: Prospective study of mortality. SETTING: A cohort study of health and aging. PARTICIPANTS: Three thousand twenty-seven community-dwelling women from the Study of Osteoporotic Fractures cohort (mean age 84). MEASUREMENTS: Activity data were collected using wrist actigraphy for a minimum of three 24-hour periods, and circadian activity rhythms were computed. Parameters of interest included height of activity peak (amplitude), midline estimating statistic of rhythm (mesor), strength of activity rhythm (robustness), and time of peak activity (acrophase). Vital status, with cause of death adjudicated through death certificates, was prospectively ascertained. RESULTS: Over an average of 4.1 years of follow-up, there were 444 (14.7%) deaths. There was an inverse association between peak activity height and all-cause mortality rates, with higher mortality rates observed in the lowest activity quartile (hazard ratio (HR)=2.18, 95% confidence interval (CI)=1.63,2.92) than in the highest quartile after adjusting for age, clinic site, race, body mass index, cognitive function, exercise, instrumental activity of daily living impairments, depression, medications, alcohol, smoking, self-reported health status, married status, and comorbidities. A greater risk of mortality from all causes was observed for those in the lowest quartiles of mesor (HR=1.71, 95% CI=1.29,2.27) and rhythm robustness (HR=1.97, 95% CI=1.50,2.60) than for those in the highest quartiles. Greater mortality from cancer (HR=2.09, 95% CI=1.04,4.22) and stroke (HR=2.64, 95% CI=1.11,6.30) was observed for later peak activity (after 4:33 p.m.; >1.5 SD from mean) than for the mean peak range (2:50,4:33 p.m.). CONCLUSION: Older women with weak circadian activity rhythms have higher mortality risk. If confirmed in other cohorts, studies will be needed to test whether interventions (e.g., physical activity, bright light exposure) that regulate circadian activity rhythms will improve health outcomes in older adults. [source] Seasonal activity and abundance of Orosius orientalis (Hemiptera: Cicadellidae) at agricultural sites in Southeastern AustraliaJOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2010P. Tr, bicki Abstract Orosius orientalis is a leafhopper vector of several viruses and phytoplasmas affecting a broad range of agricultural crops. Sweep net, yellow pan trap and yellow sticky trap collection techniques were evaluated. Seasonal distribution of O. orientalis was surveyed over two successive growing seasons around the borders of commercially grown tobacco crops. Orosius orientalis seasonal activity as assessed using pan and sticky traps was characterised by a trimodal peak and relative abundance as assessed using sweep nets differed between field sites with peak activity occurring in spring and summer months. Yellow pan traps consistently trapped a higher number of O. orientalis than yellow sticky traps. [source] Lactic acid fermentation of food waste using integrated glucoamylase productionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2009Xiao Qiang Wang Abstract Commercial enzyme is usually needed for the bioconversion of organic waste or biomass. The overall cost could be reduced very significantly if enzyme production could be integrated with its application, avoiding unnecessary steps in enzyme production (such as concentration, recovery and transportation). This investigation attempted to integrate crude glucoamylase production with lactic acid fermentation of food waste. A maximum glucoamylase activity of 1850 U g,1 was obtained with Aspergillus nigerduring solid-state fermentation (SSF) of food waste, 14.8 times more than that obtained during submerged fermentation (SmF). The optimum pH for producing glucoamylase was 4.6, and glucoamylase retained 83.5% of peak activity at pH 3.0. Without any recovery treatment, the glucoamylase produced by SSF could be used directly for lactic acid fermentation of food waste. Lactic acid concentration reached 45.5 g L,1 with the addition of the crude enzyme, 72% higher than the control. No side-effects were caused by the viable A. niger in the crude enzyme. This work successfully integrated glucoamylase production with lactic acid fermentation. The enzyme produced by SSF of food waste had sufficient activity to be used directly without any treatment. The integrated process proposed in this study was very economical and may be helpful to other bioconversions. Copyright © 2008 Society of Chemical Industry [source] Comparative study on proteolysis of two species of bigeye snapper, Priacanthus macracanthus and Priacanthus tayenusJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2003Soottawat Benjakul Abstract Proteolytic activity in muscle from two species of bigeye snapper (Priacanthus macracanthus and Priacanthus tayenus) was studied. Autolysis of mince and washed mince at 50 and 60 °C was compared. Higher degradation of myosin heavy chain was observed in both mince and washed mince from P macracanthus than in those from P tayenus, especially when the incubation time was increased. Autolysis of washed mince from both species was inhibited by soybean trypsin inhibitor, suggesting that myofibril-associated proteases were serine proteases. When sarcoplasmic proteolytic activity in P macracanthus muscle was studied, two activity peaks with an optimum temperature of 60 °C were observed at pH 6.5 and 8.5. The activities of both peaks were mostly inhibited by soybean trypsin inhibitor, suggesting that the major protease was a serine protease. Major sarcoplasmic proteolytic activity in P macracanthus muscle was found at Mr 62 000 on sodium dodecyl sulphate substrate gel. For P tayenus sarcoplasmic proteolytic activity, two activity peaks with an optimum temperature of 60 °C were found at pH 5.0 and 8.5. The pH 5.0 peak activity was effectively inhibited by pepstatin A, while the pH 8.5 peak activity was inhibited by several inhibitors. The results indicated that various sarcoplasmic proteases were present in P tayenus muscle. The two species contained different sarcoplasmic proteases in terms of composition and activity level. P macracanthus muscle generally had higher sarcoplasmic proteolytic activities than P tayenus muscle. Copyright © 2003 Society of Chemical Industry [source] Heterologous production of the Piromyces equi cinnamoyl esterase in Trichoderma reesei for biotechnological applicationsLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2009L. Poidevin Abstract Aims:, The objective of the study was to produce and characterize the cinnamoyl esterase EstA from the anaerobic fungus Piromyces equi for potential industrial applications. Methods and Results:, The catalytic domain EstA was produced in Trichoderma reesei. Because the two fungi displayed different genome features, including different codon usage and GC content, a synthetic gene was designed and expressed, leading to the production of the corresponding protein at around 33 mg per litre in the T. reesei culture medium. After the recombinant protein was purified, biochemical characterization showed that EstA presents peak activity at pH 6·5 and at 50,60°C. Furthermore, EstA remained stable at pH 6,8 and below 50°C. EstA was compared to cinnamoyl esterases FaeA and FaeB from Aspergillus niger in terms of ferulic acid (FA) release from wheat bran (WB), maize bran (MB) and sugar beet pulp (SBP). Conclusion:, The synthetic gene was successfully cloned and overexpressed in T. reesei. EstA from P. equi was demonstrated to efficiently release FA from various natural substrates. Significance and Impact of the Study:, Recombinant EstA produced in an industrial enzyme producer, T. reesei, was biochemically characterized, and its capacity to release an aromatic compound (FA) for biotechnological applications was demonstrated. [source] | ||||||||||||||||