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Articoli di riviste sul tema "Active oxygen – Physiological effect"
1
Colon, Marcus, Andrew Hodgson, Eimear Donlon e James E. J. Murphy. "Effects of Competitive Triathlon Training on Telomere Length". Journal of Aging and Physical Activity 27, n. 4 (1 agosto 2019): 510–14. http://dx.doi.org/10.1123/japa.2018-0248.
Testo completoAbstract (sommario):
Telomeres act as a mitotic clock and telomere-related senescence has been linked to age-related physiological decline. There is increasing evidence lifestyle factors can influence telomere length (TL). The purpose of this study was to determine the effect of competitive triathlon training on TL. Seven competitive male triathletes and seven recreationally active males participated in the study. Relative TL was measured using quantitative polymerase chain reaction. Physiological parameters key to athletic performance such as maximal oxygen intake, lactate threshold, and running economy were also measured. Triathletes had longer telomeres than the recreationally active (1.257 ± 0.028 vs. 1.002 ± 0.014; p < .0001). Positive association was found between TL and maximal oxygen intake, lactate threshold, and running economy (R2 = .677, .683, and .696, respectively). This study indicates that competitive triathlon training buffers against age-related telomere shortening, and there is a correlation between exercise behaviors, higher maximal oxygen intake, and TL.
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Madueno, Maria C., Vincent J. Dalbo, Joshua H. Guy, Kate E. Giamarelos, Tania Spiteri e Aaron T. Scanlan. "Reduced Fatigue in Passive Versus Active Recovery: An Examination of Repeated-Change-of-Direction Sprints in Basketball Players". International Journal of Sports Physiology and Performance 13, n. 8 (1 settembre 2018): 1034–41. http://dx.doi.org/10.1123/ijspp.2017-0831.
Testo completoAbstract (sommario):
Purpose: To investigate the physiological and performance effects of active and passive recovery between repeated-change-of-direction sprints. Methods: Eight semiprofessional basketball players (age: 19.9 [1.5] y; stature: 183.0 [9.6] cm; body mass: 77.7 [16.9] kg; body fat: 11.8% [6.3%]; and peak oxygen consumption: 46.1 [7.6] mL·kg−1·min−1) completed 12 × 20-m repeated-change-of-direction sprints (Agility 5-0-5 tests) interspersed with 20 seconds of active (50% maximal aerobic speed) or passive recovery in a randomized crossover design. Physiological and perceptual measures included heart rate, oxygen consumption, blood lactate concentration, and rating of perceived exertion. Change-of-direction speed was measured during each sprint using the change-of-direction deficit (CODD), with summed CODD time and CODD decrement calculated as performance measures. Results: Average heart rate (7.3 [6.4] beats·min−1; P = .010; effect size (ES) = 1.09; very likely) and oxygen consumption (4.4 [5.0] mL·kg−1·min−1; P = .12; ES = 0.77; unclear) were moderately greater with active recovery compared with passive recovery across sprints. Summed CODD time (0.87 [1.01] s; P = .07; ES = 0.76, moderate; likely) and CODD decrement (8.1% [3.7%]; P < .01; ES = 1.94, large; almost certainly) were higher with active compared with passive recovery. Trivial–small differences were evident for rating of perceived exertion (P = .516; ES = 0.19; unclear) and posttest blood lactate concentration (P = .29; ES = 0.40; unclear) between recovery modes. Conclusions: Passive recovery between repeated-change-of-direction sprints may reduce the physiological stress and fatigue encountered compared with active recovery in basketball players.
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Carmeli, Eli, Pini Orbach, David T. Lowenthal, Joav Merrick e Raymond Coleman. "Long-Term Effects of Activity Status in the Elderly on Cardiorespiratory Capacity, Blood Pressure, Blood Lipids, and Body Composition: A Five-Year Follow-Up Study". Scientific World JOURNAL 3 (2003): 751–67. http://dx.doi.org/10.1100/tsw.2003.66.
Testo completoAbstract (sommario):
It is generally recognized that physical activity levels in the elderly do not remain constant over time, and typically there is a marked reduction in physical activities in the elderly. The long-term benefits of regular physical training programs in the elderly are still not fully understood. This is a study of 55 elderly healthy subjects (over 65 years old) and re-evaluated for the effects of different physical activity patterns (sedentary, moderately active, and highly active) on several physiological parameters (pre- and post-training) after a 5-year period (5.30 ± 1.14 years). Measurements included: body composition, blood lipid profiles, resting systolic and diastolic blood pressure, maximal oxygen uptake, and pulmonary function. Results indicated a larger decrease in maximal oxygen uptake (VO2max) in the group of elderly sedentary individuals (1.5 ± 0.5 l/min) compared to the moderately active (1.7 ± 0.6 l/min) and the highly active groups (1.9 ± 0.4 l/min). An active lifestyle was not sufficient to increase the physiological function of an individual.This study could not clearly demonstrate favorable differences for the physically active groups over the sedentary group with regard to several important physiological factors over the 5-year follow-up and it appears that the recommendation for, and the initiation of, adopting active lifestyles may not be sufficient on their own to significantly increase an individual's physiological functioning.
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Reid, MB. "Reactive Oxygen and Nitric Oxide in Skeletal Muscle". Physiology 11, n. 3 (1 giugno 1996): 114–19. http://dx.doi.org/10.1152/physiologyonline.1996.11.3.114.
Testo completoAbstract (sommario):
Skeletal muscle produces oxygen radicals, nitric oxide, and a variety of redox-active derivatives that modulate muscle function under physiological conditions. In unfatigued muscle, reactive oxygen intermediates and nitric oxide exert opposing effects on excitation-contraction coupling. During strenuous exercise, oxidants accumulate in the tissue and accelerate the fatigue process.
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Rubalcaba, Juan G., Wilco C. E. P. Verberk, A. Jan Hendriks, Bart Saris e H. Arthur Woods. "Oxygen limitation may affect the temperature and size dependence of metabolism in aquatic ectotherms". Proceedings of the National Academy of Sciences 117, n. 50 (30 novembre 2020): 31963–68. http://dx.doi.org/10.1073/pnas.2003292117.
Testo completoAbstract (sommario):
Both oxygen and temperature are fundamental factors determining metabolic performance, fitness, ecological niches, and responses of many aquatic organisms to climate change. Despite the importance of physical and physiological constraints on oxygen supply affecting aerobic metabolism of aquatic ectotherms, ecological theories such as the metabolic theory of ecology have focused on the effects of temperature rather than oxygen. This gap currently impedes mechanistic models from accurately predicting metabolic rates (i.e., oxygen consumption rates) of aquatic organisms and restricts predictions to resting metabolism, which is less affected by oxygen limitation. Here, we expand on models of metabolic scaling by accounting for the role of oxygen availability and temperature on both resting and active metabolic rates. Our model predicts that oxygen limitation is more likely to constrain metabolism in larger, warmer, and active fish. Consequently, active metabolic rates are less responsive to temperature than are resting metabolic rates, and metabolism scales to body size with a smaller exponent whenever temperatures or activity levels are higher. Results from a metaanalysis of fish metabolic rates are consistent with our model predictions. The observed interactive effects of temperature, oxygen availability, and body size predict that global warming will limit the aerobic scope of aquatic ectotherms and may place a greater metabolic burden on larger individuals, impairing their physiological performance in the future. Our model reconciles the metabolic theory with empirical observations of oxygen limitation and provides a formal, quantitative framework for predicting both resting and active metabolic rate and hence aerobic scope of aquatic ectotherms.
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Molina-Sotomayor, Edgardo, Marcelo González Orb, Francisco Pradas de la Fuente, Giovanni Carozzi Figueroa, Antonio Sánchez-Oliver e José González-Jurado. "Effects of Cardiorespiratory Exercise on Cognition in Older Women Exposed to Air Pollution". International Journal of Environmental Research and Public Health 16, n. 2 (16 gennaio 2019): 245. http://dx.doi.org/10.3390/ijerph16020245.
Testo completoAbstract (sommario):
The aim was to analyze the effects of cardiorespiratory exercise and air pollution on cognition and cardiovascular markers in four groups of older women: the active/clean air group (AC), the active/polluted air group (AP), the sedentary/clean air group (SC), and the sedentary/polluted air group (SP). Active groups performed a training task based on progressive walking. Prior to and after the experiment, the following parameters were assessed: cognition, by Mini Mental State Examination (MMSE); maximum oxygen uptake (VO2max), estimated by the Six-Minute Walk Test (6mWT); heart rate (HR); and oxygen saturation (SpO2). There were significant differences (p < 0.05) between the AC and the SP in all the MMSE dimensions except “Registration”, and in all the physiological variables (VO2max, SpO2, HR). Aerobic exercise may be a protective factor against the effects that pollution have on cognition and on the mechanisms of oxygen transport.
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Losnegard, Thomas, Martin Andersen, Matt Spencer e Jostein Hallén. "Effects of Active Versus Passive Recovery in Sprint Cross-Country Skiing". International Journal of Sports Physiology and Performance 10, n. 5 (luglio 2015): 630–35. http://dx.doi.org/10.1123/ijspp.2014-0218.
Testo completoAbstract (sommario):
Purpose:To investigate the effects of an active and a passive recovery protocol on physiological responses and performance between 2 heats in sprint cross-country skiing.Methods:Ten elite male skiers (22 ± 3 y, 184 ± 4 cm, 79 ± 7 kg) undertook 2 experimental test sessions that both consisted of 2 heats with 25 min between start of the first and second heats. The heats were conducted as an 800-m time trial (6°, >3.5 m/s, ~205 s) and included measurements of oxygen uptake (VO2) and accumulated oxygen deficit. The active recovery trial involved 2 min standing/walking, 16 min jogging (58% ± 5% of VO2peak), and 3 min standing/walking. The passive recovery trial involved 15 min sitting, 3 min walk/jog (~ 30% of VO2peak), and 3 min standing/walking. Blood lactate concentration and heart rate were monitored throughout the recovery periods.Results:The increased 800-m time between heat 1 and heat 2 was trivial after active recovery (effect size [ES] = 0.1, P = .64) and small after passive recovery (ES = 0.4, P = .14). The 1.2% ± 2.1% (mean ± 90% CL) difference between protocols was not significant (ES = 0.3, P = .3). In heat 2, peak and average VO2 was increased after the active recovery protocol.Conclusions:Neither passive recovery nor running at ~58% of VO2peak between 2 heats changed performance significantly.
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Milovanova, Tatyana N., Veena M. Bhopale, Elena M. Sorokina, Jonni S. Moore, Thomas K. Hunt, Martin Hauer-Jensen, Omaida C. Velazquez e Stephen R. Thom. "Hyperbaric oxygen stimulates vasculogenic stem cell growth and differentiation in vivo". Journal of Applied Physiology 106, n. 2 (febbraio 2009): 711–28. http://dx.doi.org/10.1152/japplphysiol.91054.2008.
Testo completoAbstract (sommario):
We hypothesized that oxidative stress from hyperbaric oxygen (HBO2, 2.8 ATA for 90 min daily) exerts a trophic effect on vasculogenic stem cells. In a mouse model, circulating stem/progenitor cell (SPC) recruitment and differentiation in subcutaneous Matrigel were stimulated by HBO2and by a physiological oxidative stressor, lactate. In combination, HBO2and lactate had additive effects. Vascular channels lined by CD34+SPCs were identified. HBO2and lactate accelerated channel development, cell differentiation based on surface marker expression, and cell cycle entry. CD34+SPCs exhibited increases in thioredoxin-1 (Trx1), Trx reductase, hypoxia-inducible factors (HIF)-1, -2, and -3, phosphorylated mitogen-activated protein kinases, vascular endothelial growth factor, and stromal cell-derived factor-1. Cell recruitment to Matrigel and protein synthesis responses were abrogated by N-acetyl cysteine, dithioerythritol, oxamate, apocynin, U-0126, neutralizing anti-vascular endothelial growth factor, or anti-stromal cell-derived factor-1 antibodies, and small inhibitory RNA to Trx reductase, lactate dehydrogenase, gp91phox, HIF-1 or -2, and in mice conditionally null for HIF-1 in myeloid cells. By causing an oxidative stress, HBO2activates a physiological redox-active autocrine loop in SPCs that stimulates vasculogenesis. Thioredoxin system activation leads to elevations in HIF-1 and -2, followed by synthesis of HIF-dependent growth factors. HIF-3 has a negative impact on SPCs.
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Dehghani, Hamed, Mohammad Ali Oghabian, Seyed Amir Hosein Batouli, Jalil Arab Kheradmand e Ali Khatibi. "Effect of Physiological Noise on Thoracolumbar Spinal Cord Functional Magnetic Resonance Imaging in 3T Magnetic Field". Basic and Clinical Neuroscience Journal 11, n. 6 (1 novembre 2020): 737–52. http://dx.doi.org/10.32598/bcn.11.6.1395.1.
Testo completoAbstract (sommario):
Introduction: Functional magnetic resonance imaging (fMRI) methods have been used to study sensorimotor processing in the spinal cord. However, these techniques confront unwanted noises to the measured signal from the physiological fluctuations. In the spinal cord imaging, most of the challenges are consequences of cardiac and respiratory movement artifacts that are considered as significant sources of noise, especially in the thoracolumbar region. In this study, we investigated the effect of each source of physiological noise and their contribution to the outcome of the analysis of the blood-oxygen-level-dependent signal in the human thoracolumbar spinal cord. Methods: Fifteen young healthy male volunteers participated in the study, and pain stimuli were delivered on the L5 dermatome between the two malleoli. Respiratory and cardiac signals were recorded during the imaging session, and the generated respiration and cardiac regressors were included in the general linear model for quantification of the effect of each of them on the task-analysis results. The sum of active voxels of the clusters was calculated in the spinal cord in three correction states (respiration correction only, cardiac correction only, and respiration and cardiac noise corrections) and analyzed with analysis of variance statistical test and receiver operating characteristic curve. Results: The results illustrated that cardiac noise correction had an effective role in increasing the active voxels (Mean±SD= 23.46±9.46) compared to other noise correction methods. Cardiac effects were higher than other physiological noise sources Conclusion: In summary, our results indicate great respiration effects on the lumbar and thoracolumbar spinal cord fMRI, and its contribution to the heartbeat effect can be a significant variable in the individual fMRI data analysis. Displacement of the spinal cord and the effects of this noise in the thoracolumbar and lumbar spinal cord fMRI results are significant and cannot be ignored.
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Mikalački, Milena, Nebojša Čokorilo e Pedro Jesús Ruiz-Montero. "The effects of a pilates-aerobic program on maximum exercise capacity of adult women". Revista Brasileira de Medicina do Esporte 23, n. 3 (maggio 2017): 246–49. http://dx.doi.org/10.1590/1517-869220172303156004.
Testo completoAbstract (sommario):
ABSTRACT Introduction: Physical exercise such as the Pilates method offers clinical benefits on the aging process. Likewise, physiologic parameters may be improved through aerobic exercise. Methods: In order to compare the differences of a Pilates-Aerobic intervention program on physiologic parameters such as the maximum heart rate (HRmax), relative maximal oxygen consumption (relative VO2max) and absolute (absolute VOmax), maximum heart rate during maximal oxygen consumption (VO2max-HRmax), maximum minute volume (VE) and forced vital capacity (FVC), a total of 64 adult women (active group = 48.1 ± 6.7 years; control group = 47.2 ± 7.4 years) participated in the study. The physiological parameters, the maximal speed and total duration of test were measured by maximum exercise capacity testing through Bruce protocol. The HRmax was calculated by a cardio-ergometric software. Pulmonary function tests, maximal speed and total time during the physical test were performed in a treadmill (Medisoft, model 870c). Likewise, the spirometry analyzed the impact on oxygen uptake parameters, including FVC and VE. Results: The VO2max (relative and absolute), VE (all, P<0.001), VO2max-HRmax (P<0.05) and maximal speed of treadmill test (P<0.001) showed significant difference in the active group after a physical exercise interventional program. Conclusion: The present study indicates that the Pilates exercises through a continuous training program might significantly improve the cardiovascular system. Hence, mixing strength and aerobic exercises into a training program is considered the optimal mechanism for healthy aging.
Tesi sul tema "Active oxygen – Physiological effect"
1
Gutowski, Mariusz. "Molecular detection and characterisation of biologically relevant free radicals during surgical ischaemia-reperfusion". Thesis, University of South Wales, 2011. https://pure.southwales.ac.uk/en/studentthesis/molecular-detection-and-charcaterisation-of-biologically-relevant-free-radicals-during-surgical-ischaemiareperfusion(016f6447-5d02-45f7-a543-8b880148dc23).html.
Testo completoAbstract (sommario):
Oxygen is one of the most important molecules in human beings. Our research is focused on how the human body can respond and adapt to the physiological challenge posed by a lack of oxygen. Ascorbic acid (Vitamin C) is one of the most important and considered the most effective water-soluble, chain-breaking antioxidant in human plasma, with the capacity to prevents damage by free radicals. This thesis presents four studies investigating the phenomenon of Reactive Oxygen Species (ROS) generation in the many different surgical conditions in the animal and in the human. Study one investigated the geometry and thermodynamic properties of vitamin C. Calculations were carried out at the restricted and unrestricted B3LYP/6-31+G(d,p), B3LYP/6-311++G(d,p) and B3LYP/EPR-II levels for two conformers (1 and 2) of L-ascorbic acid and their respective oxidation products to monodehydroascorbates of ab-initio methods by Gaussian O3W package. Conformer 1, free radical properties are compared with previously published calculations in the gaseous and aqueous solution states and with experimental EPR values. Calculated molecular structures, EPR (electron paramagnetic resonance spectroscopy), the vibration spectral and energetic properties and all are reported including some proposed changes to previous EPR assignments. Conformer 2 of L-ascorbic acid is predicted to have lower energy than Conformer 1, under the method and basis sets used, by between 11 and 26 kJ mol-1 and is stabilised by internal hydrogen bonding. Relaxed potential energy surface (PES) scans were carried out for two proton transfer processes and relative energies of stable minima and barriers between them determined. Hydrogen transfer is predicted in two systems with favourable spatial arrangements of O–H and O groups for which relaxed potential energy surface scans are reported. Calculated vibrational wavenumber values are provided for selected C=C, C=O, C–H and O–H modes assigned to particular groups and significant calculated EPR hyperfine coupling constants (HCC) values for splitting by H(1) and C(13) for radical species are also reported. These calculations contribute to a better understanding of the complex role of L-ascorbic acid and its various oxidised, neutral, ionic and radical forms in biochemistry and medicine. Study two examined if vitamin C could ameliorate the damaging effects of I-R on myocardium and we postulated that the mechanism of vitamin C protection against iii I-R-induced cell death involved quenching of ROS. In the vitamin C group after 5 min of reperfusion a significant, sudden increase of diastolic pressure in the heart was noted and reached a maximum of 77 mmHg after 12 min of reperfusion and then gradually decreased to 51 mmHg after 60 min of reperfusion period but was quicker than in Control group reaching 37 mmHg by the end of the reperfusion period. The level of A·− (ascorbate free radicals) sudden and massive increased at the time of reperfusion in the Vitamin C group. This increase was associated with poor mechanical function in hearts as indicated by the significantly depressed recovery process. After 30 min of global, now-flow ischaemia and 60min of reperfusion infarct size averaged 33% ± 1 in Control group and 30 % ± 1 in Vitamin C group, respectively, (P<0.05). There is strong evidence that oxygen centered radicals contribute to postischaemic dysfunction after global ischaemia. Our data unquestionably suggest that the large production of A·− was associated with a greater depression in myocardial contractile function, therefore could represent a marker of oxidative stress during I-R and could be related to the functional impairment during reperfusion. In summary, we have used the animal models of isolated heart perfusion to provide evidence that vitamin C did not reduce the infarct size, however “tendency” towards a decrease (↓) in infarct size with ascorbate and it protects from oxidative damage during global I-R as manifested by decreased concentrations of A·− and enhance recovery of mechanical function such as diastolic pressure and LVDP in postischaemic working rat hearts. Study three was designed to test the hypothesis that the physiological trauma associated with venous cannulation may artefactually stimulate systemic free radical formation in the acute phase that if not accounted for may under-estimate the oxidative stress response to exercise. The relationship between the time of venepuncture and the level of free radical generation during normoxic conditions was further investigated. The venous cannulation in Phase I, increased plasma A·− by 347 ± 173 AU/√G, P <0.05 after 2min of venepuncture with further increases observed after 5min and 10min of venous cannulation, respectively (403 ± 178 AU/√G; 462 ± 93 AU/√G, P < 0.05) vs baseline point time. After this time the level of A·− slightly blunted as to achieve a similar level to baseline point control after 30 minutes. In phase II the exerciseinduced increase in A·− was subsequently shown to be 48% greater (30min as opposed to the 2min post-cannulation resting baseline)(1754 ± 361 vs. 1979 ± 375 AU, P <0.05). Our findings demonstrate and confirm that venous cannulation per se stimulates iv the systemic formation of free radicals as an acute phase response which peaks at 10min and require approximately 15min to normalise. This has important interpretive implications for future studies that employ catheterisation. The final Study examined if the combination of exercise and inspiratory hypoxia would further compound regional tissue de-oxygenation that is frequently encountered during the ischaemic phase of surgery and thus, by consequence increase oxidative stress. The aim of the study was to further understand a potential relationship between oxidative stress and alterations in muscle oxygenation. Clear significant increases in the plasma concentration of A·− were detected in the peripheral blood of patients (normoxia(baseline) vs 6 data points of reperfusion after 5min of global ischaemic condition, P<0.05),(baseline vs immediate after ischaemia; 2337±525 vs 2633±508, AU, respectively). During global ischaemia the regional muscle oxygenation significantly decreased (↓∆O2Hb-oxyhaemoglobin), ↑∆HHb- deoxyhaemoglobin ), although increased regional blood volume (↑∆tHb- total haemoglobin). From the end of global ischaemia to 10 min after the regional muscle oxygenation progressively back to the start data point (↓∆HHb, ↑∆O2Hb). This study demonstrates for the first time that the I-R has got a big influence on the muscle oxygenation to increased ROS and the return of values towards baseline period in reperfusion stage appears to coincide with increased oxidative stress. Moreover, the present study has also demonstrated increased A·− level as early as the ischaemic phase of experiment independent of perioperative changes in the partial pressure of oxygen (pO2), elucidate a potentially important role for oxidative stress in provoking an appropriate vasodilation (NO-bioavailability) during the I-R period. This work demonstrates that; - Ascorbate is an antioxidant that can scavenge tissue and blood borne free radical, is essential in controlled amounts and is capable of initiating protective adaptation in the face of oxidative stress for the maintenance of physiological homeostasis. - Reperfusion is always associated with a sudden and massive release of ascorbate free radicals, with a maximal liberation within the first minutes of reperfusion. Vitamin C tended to reduce infarct size and protects from oxidative damage during global ischaemia and reperfusion. - The venous cannulation alone is enough per se stimulates the systemic formation of free radicals as a acute phase response. If this baseline artefact is not taken into account, the true magnitude of the exercise-induced oxidative stress response will be under-estimated.The I-R has got a major influence on the muscle oxygenation to increased ROS and the return of values towards baseline period in reperfusion stage appears to coincide with increased oxidative stress. Using the state-of-the-art molecular techniques that include Electron Paramagnetic Spectroscopy (EPR) for the direct detection of free radicals and Near Infrared Spectroscopy (NIRS) for the direct detection of muscle oxygenation these studies have attempted to translate the basic mechanisms associated with free radical formation during I-R and have provided unique insight into the basic mechanisms responsible for the oxidative stress with the ultimate objective of developing novel antioxidant interventions that can provide effective prophylaxis.
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Wu, Wan Man. "Reactive oxygen species and murine malaria". Thesis, The University of Sydney, 1992. https://hdl.handle.net/2123/26446.
Testo completoAbstract (sommario):
The aim of this study was to investigate the role of ROS in the protective and pathological immune response during malarial infection. For this purpose, four isolates of Plasmodium parasites (P. berghei ANKA, P. vinckei, P. berghei K152 and P. chabaudi) and two different inbred strains of mice (CBA and DBA) were used.
The patterns of mortality varied between the different mouseparasite strain combinatio ns. The mortality of CBA mice infected with P. vinckei and P. berghei K152, and DBA mice infected with P. berghei ANKA, related to the levels of parasitaemia. However early mortality of CBA mice infected with P. berghei ANKA did not relate to the parasitaem ia level but to the onset of neurologica l symptoms. Over 90% of P. chabaudi—infected CBA mice recovered from the infection.
The morphologi cal examinatio n of brain tissues obtained from P. berghei ANKA-infec ted CBA mice on day 7 post-inocul ation showed haemorrag e, oedema and the infiltration of mononucle ar cells. Measurement of the permeability of the blood-brain barrier by injection of Evans blue showed the dye leaking into the brain parenchyma, suggesting a dysfunction of the barrier in this mouse model.
The hypothesis that ROS play a role in the anti—malaria response was supported by previous studies demonstrati ng that malaria parasites are killed by ROS in vivo and in vitro (reviewed in Hunt & Stocker. 1990). To further test the hypothesis. the oxidative burst ability of splenic macrophage s and peripheral monocytes taken from different mouse-para site strain combinations was examined.
There was a significant increase of superoxide production by splenic macrophag es at the early stage of all the infections and the spleen weight gradually increased during all the infections. Furthermore, the oxidative burst ability of monocytes was significantly increased in the late stage of all the infections, which was accompanied by increased peripheral WBC numbers, especially in the numbers of monocytes and PMNs in all the infections except the P. berghei ANKA infection in CBA mice.
Of the four strains of parasites infecting CBA mice, the self-resol ving P. Chabaudi infection induced the greatest PMA-stimulable response superoxide anion production on certain days after parasite in inoculation in both splenic macrophages and monocytes . Conversely, the P. vinckei infection induced the lowest response, which may partly explain why the parasites generated faster in these mice than in the other three strains.
Malaria parasites are able to induce immunosup pression at the early stage of infection as shown by the decline in the total number of WBC and the decrease of superoxide production by monocytes. This immunosuppresion may help explain why the parasites can survive even when their numbers are. small.
TNF and IFN—y are known as major mediatory factors involved in the development of cerebral malaria. This was supported by the cytokine gene expression studies which showed that both TNF and IFN-y mRNAs were expressed in the brains of mice with cerebral malaria. These cytokines may stimulate mononuclear phagocytes to produce other soluble factors to cause cerebral damage.
ROS release d from mononuclear phagocytes are thought to be crucial factors involved in the development of cerebral malaria (Hunt et al., 1991). However , the oxidative burst ability of splenic macrophages and monocytes in the P. berghei—ANKA infected CBA mice, which suffered cerebral malaria and died early in the infection, was lower than that in the same infection in DBA mice which recovered from the cerebral lesion but died at a later stage of infection with a high level of parasitaemia. Further more, lipid peroxidation studies showed that there was no significant difference in brain MDA formation between control mice and the mice with cerebral malaria . These results fail to provide evidence for a role of ROS in the development of cerebral malaria . Further studies to investigate lipid peroxidation and redox. status of the brain in cerebral malaria using HPLC are required.
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Harris, Jessica. "BODIPY dyes for singlet oxygen and optical limiting applications". Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/58002.
Testo completoAbstract (sommario):
A series of structurally related BODIPY dyes were synthesised and characterised. Their photophysical properties were studied in order to determine whether they would be suitable candidates for use as photosensitisers in the photodynamic therapy (PDT) treatment of cancer. The synthesis of two highly fluorescent BODIPY cores was achieved via the acid-catalysed condensation of a pyrrole and a functionalised aldehyde. In order to promote intersystem crossing, and hence improve the singlet oxygen generation of these dyes, bromine atoms were added at the 2,6-positions of the BODIPY core. These dibrominated analogues showed good singlet oxygen quantum yields, and excellent photostability in ethanol. In order to red-shift the main spectral bands of the BODIPY dyes towards the therapeutic window, vinyl/ styryl groups were introduced at the 3-, 5-, and 7-positions via a modified Knoevengal condensation reaction. The addition of vinyl/ styryl groups to the BODIPY core caused an increase in fluorescence quantum yield as well as a decrease in singlet oxygen quantum yield with respect to the dibrominated analogues. However, two of the red-shifted BODIPY dyes still showed moderate singlet oxygen quantum yields. The use of BODIPY dyes in nonlinear optics (NLO) was explored. The nonlinear optical characterisations and optical limiting properties of a series of 3,5-dithienylenevinylene BODIPY dyes were studied, both in dimethylformamide (DMF) solution and when embedded in poly(bisphenol A carbonate) (PBC) as thin films. The 3,5-dithienylenevinylene BODIPY dyes showed typical nonlinear absorption behaviour, with reverse saturable absorption (RSA) profiles, indicating that they have potential as optical limiters. The second-order hyperpolarizability (Y), and third-order nonlinear susceptibility (/m[/(3)]) values are also reported for these dyes. The optical limiting values of one of the BODIPY dyes in solution, and two of the BODIPY-embedded PBC films, were below the maximum threshold of 0.95 J-cm-2. The effect of addition of substituents on the electronic structure of the BODIPY dyes was investigated using TD-DFT calculations. The calculated trends closely followed those determined experimentally.
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Seotsanyana-Mokhosi, Itumeleng. "Photosensitizing properties of non-transition metal porphyrazines towards the generation of singlet oxygen". Thesis, Rhodes University, 2001. http://hdl.handle.net/10962/d1006086.
Testo completoAbstract (sommario):
Metallophthalocyanine complexes containing non-transition metals are very useful as sensitizers for photodynamic therapy, a cure for cancer that is based on visible light activation of tumour localized photo sensitizers. Excited sensitizers generate singlet oxygen as the main hyperactive species that destroy the tumour. Water soluble sensitizers are sought after for the convenience of delivery into the body. Thus, phthalocyanine (pc), tetrapyridinoporphyrazines (tppa) and tetramethyltetrapyridinoporphyrazines (tmtppa) with non-transition central metal atoms of Ge, Si, Sn and Zn were studied. First was the synthesis of these complexes, followed by their characterisation. The characterisation involved the use of ultraviolet and visible absorption spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, electrochemical properties and elemental analysis. Photochemical properties of the complexes were then investigated. Photolysis of these macrocycles showed two processes; -reduction of the dye and photobleaching, which leads to the disintegration of the conjugated chromophore structure of the dye. Photobleaching is the reductive quenching of the excited state of the sensitizers. The intensity of the quenching decreased progressively from tmtppa, tppa to pc metal complexes with photobleaching quantum yields, 6.6 x 10.5⁻¹, 1.8 x 10.5⁻¹ and 5.4 x 10⁻⁶ for Zntmtppa, Zntppa and Znpc, respectively. Efficiency of singlet oxygen sensitization is solvent dependent with very different values obtained for the same compound in different solvents, for example, 0.25 and 0.38 were observed as singlet oxygen quantum yields for Gepc complex in DMSO and DMF respectively. In DMSO the efficiency of ¹O₂ generation decrease considerably from pc to tppa and finally tmtppa. In water Getmtppa exhibits much higher singlet oxygen quantum yield, hence promising to be effective as a sensitizer for photodynamic therapy.
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Bucknall, Martin Paul Medical Sciences Faculty of Medicine UNSW. "Dityrosine as a biomarker of free radical induced oxidative damage in diseases of ageing". Awarded by:University of New South Wales. School of Medical Sciences, 2006. http://handle.unsw.edu.au/1959.4/30207.
Testo completoAbstract (sommario):
o,o???-Dityrosine (dityrosine), an oxidation product of tyrosine produced by reaction between tyrosyl radicals, is becoming established as a biomarker of free radical oxidative protein damage in vivo. Attempts to measure dityrosine concentrations in various physiological and pathological systems have produced varied and often contradictory results. Dityrosine concentrations in urine, plasma, cerebrospinal fluid (CSF) and brain tissue varying over three orders of magnitude have been reported, together with inconsistent claims of significant dityrosine elevation in several ageing-related pathologies. Some of these findings have contributed to the implication of free radical activity in the pathology of several neurodegenerative disorders, vascular and ocular abnormalities and in phagocyte response to infection. The aim of this study was to test the hypothesis that dityrosine levels are elevated in ageing and ageing-related disease. The study also aims to determine the utility of dityrosine measurement as an index of oxidative damage, and elucidate possible explanations for the inconsistent levels reported. An assay for the quantification of dityrosine was developed using capillary HPLC with electrospray tandem quadrupole mass spectrometry (HPLC-MS/MS). The assay was highly specific for dityrosine and has the highest absolute sensitivity for dityrosine of any method reported to date, with a detection limit of 3 femtomoles of dityrosine on-column. Urine samples from volunteers of different age and from hospital patients with various pathologies were analysed. Plasma protein hydrolysates from control, Alzheimer???s and stroke subjects were analysed, together with hydrolysates of post mortem brain tissue from Alzheimer???s and control subjects. Urinary dityrosine level is elevated in states of acute infection and inflammation, but does not correlate with age or chronic disease. Protein dityrosine in four sections of Alzheimer???s brain was not significantly different from control sections. Dityrosine was present in human plasma and tissue proteins at approximately 5-35 residues per million tyrosine residues, and in normal urine at 5-25 micromol/mol creatinine or 20-200 nM. Most of the discrepancies in the literature relate to inadequate specificity of the analytical method. Interpretation of published data with critical appraisal of measurement technology specificity is essential in developing an accurate understanding of the role of free radicals in ageing and disease.
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Feng, Jinliu 1974. "Mitochondrial respiratory transportation is the key determinant of aging in Caenorhabditis elegans". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32991.
Testo completoAbstract (sommario):
'The rate of living' hypothesis of aging speculates that the metabolic rate of a species ultimately determines its life expectancy. Using the nematode worm Caenorhabditis elegans as model system, mutation in twp-1 (t&barbelow;ime w&barbelow;arp) gene was found to significantly delay biological timing and remarkably increase mean and maximum life span. The rate of living in twp-1 is dramatically delayed in all the biological processes we tested, including rates of rhythmic adult behaviors, development, and reproduction. Oxygen consumption, which indicates metabolic rate of an organism, is reduced to approximately two-fold in twp-1 mutant. According to my study, twp-1 and dauer genes, daf-2 and daf-16, interact to determine biological timing and adult life span. twp-1 mutation prolongs life span in a way that is at least partially different from dauer formation mutants, whose longevity might due to their high resistance to stresses, especially oxidative stress. twp-1 gene is cloned and found to encode iron-sulfur protein (ISP) in complex III, which is the major site of mitochondrial superoxide radical production, of the mitochondrial respiratory chain. This suggests that twp-1 may live long because they produce less reactive oxygen species (ROS), and thus, result in less oxidative damage. mts-1 (mitochondrial twp-1 suppressor) mutation can fully or partially rescue most of the biological timing in twp-1 mutant, including both developmental and behavioral rates, but except life span. mts-1 encodes another subunit of complex III, cytochrome b, which normally interact with ISP during function. mts-1 might somehow restore the activity of complex III, and consequently, accelerate the rate of living. Paraquat, a herbicide that induces the formation of superoxide, was used to provide an acute oxidative stress to animals. twp-1; mts-1 was found to be highly resistant to paraquat, indicating that twp-1 animals are well capable of coping with oxidative stress. According to o
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Lee, Fung-kwan, e 李鳳群. "Effects of æ-Lipoic acid on injury, production of nitric oxide and expression of caveolin-3 in the isolated rat heart subjected toischaemia and reperfusion". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30213915.
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Smith, Samson William. "Effects of Reactive Oxygen Species on Life History Traits of Caenorhabditis elegans". PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/712.
Testo completoAbstract (sommario):
Evolutionary life history theory predicts that tradeoffs among fitness-related phenotypes will occur as a result of resource limitations and/or physiological constraints. Such tradeoffs are defined as the cost(s) incurred on one component of fitness (e.g., reproduction) by the increased expression of another fitness-related trait (e.g., longevity). Only recently have researchers begun to investigate the mechanistic bases of life history tradeoffs. A recent proposal is that reactive oxygen species (ROS) have a central role in shaping life history traits and tradeoffs. Research on disparate animal taxa has highlighted strong correlations between oxidative stress resistance and fitness-related life history traits, for example. Here, I use the model organism Caenorhabditis elegans to test several hypotheses concerning the effects of ROS on life history traits and the manifestation of life history tradeoffs. Additionally, I use heat stress and an alternate food source to explore the responses of life history traits to other forms of physiological stress. Relative fitness and other traits related to reproduction were found to be affected in mostly negative ways by increasing oxidative insult. Lifespan was surprisingly unaffected by oxidative stress, but was modified by temperature. In vivo ROS levels as measured by fluorescent microscopy reveal a tradeoff between antioxidant production and reproduction in this species.
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Callow, Lisa Jane. "Oxidative stress and antioxidant intake in HIV-related wasting". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33385.
Testo completoAbstract (sommario):
Weight loss is a common occurrence in patients with human immunodeficiency virus (HIV) and contributes to further debilitation in the acquired immune deficiency syndrome (AIDS). Wasting syndrome (WS) is defined as 10% or more unintentional weight loss from usual body weight. The etiology of WS includes alterations in metabolism, which contribute to loss of lean body mass. Cytokine driven oxidative stress may play a critical role in the metabolic pathways that lead to HIV wasting. Studies have shown that that patients infected with HIV may have a depleted antioxidant (AO) defense system, the integrity of which is needed to efficiently scavenge reactive oxygen species (ROS). It has been theorised that low AO intake may contribute to a depressed AO defense system, which drives oxidative stress (OS). In this study we examined 16 subjects who had documented WS but no active infectious process, stratified into 10 to 15% weight loss (n = 7) and over 15% weight loss (n = 9) groups, and reported on oxidative stress measures and AO intake. (Abstract shortened by UMI.)
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Seele, Maria. "Association between antioxidant status and MnSOD Ala-9Val polymorphism in trained male athletes (rugby players) and sedentary male students controlled for antioxidant intake". Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/19864.
Testo completoAbstract (sommario):
Thesis (MSc)--University of Stellenbosch, 2007.ENGLISH ABSTRACT: The human body has developed an integrated antioxidant defence system to protect against free radical damage. Acute exercise may result in the increased generation of free radicals, including reactive oxygen species, and this may overwhelm antioxidant defence systems resulting in oxidative stress. However, it has been shown that individuals who undergo regular exercise training may have improved antioxidant capacity when compared to sedentary controls. Results from research regarding the association between antioxidant capacity and exercise training are however not conclusive and further investigation is required. Therefore, the aim of this study was to investigate the association between the total plasma antioxidant status and selected plasma indicators of antioxidant status and the MnSOD Ala-9Val (-28C®T) polymorphism in trained male athletes (rugby players) and sedentary male students while controlling for dietary intake of the major antioxidants using a validated dietary assessment method. In order to address the potential confounding effect of dietary antioxidant intake on antioxidant status in the main study, a FFQ that measures vitamin C, vitamin E, carotenoid and flavonoid intake was developed. The reproducibility was assessed by the repeat administration of the FFQ (n = 38), while the va lidity was assessed using a 28-day closeended dietary record and repeated plasma vitamin C values (n = 18). Several statistical tests were conducted to compare the values obtained from the FFQ with values obtained from the various reference methods. While results from Bland-Altman plots suggested that the reproducibility and validity of FFQ was not completely satisfactory, similar mean values, moderate to strong correlation coefficients, and a high percentage of individuals classified correctly according to quartiles of intake indicated satisfactory reproducibility and validity of the FFQ in assessing antioxidant intake. Furthermore, moderate to strong validity coefficients obtained from the method of triads also indicated satisfactory validity for the FFQ. The main study involved a cross-sectional study that compared plasma vitamin C and carotenoid levels as well as total plasma antioxidant status in trained rugby players (n = 76) and sedentary male subjects (n = 39) with different MnSOD genotypes, while controlling for dietary antioxidant intake. Rugby players had significantly higher plasma vitamin C and carotenoid levels compared to sedentary students, which indicated more satisfactory plasma antioxidant status. This was also reflected in the tendency for total plasma antioxidant status (ORAC assay) to be higher in rugby players than sedentary students. MnSOD genotype did not influence plasma vitamin C and carotenoid levels or plasma total antioxidant status, with or without control for dietary antioxidant intake. Dietary vitamin C, vitamin E, carotenoid an flavonoid intake (from foods + supplements) was similar for rugby players and sedentary students and was adequate for both groups. Thus the association between antioxidant status and MnSOD genotype in rugby players and sedentary students seemed not to be influenced by dietary antioxidant intake. In conclusion therefore, rugby players undergoing regular exercise training had a more satisfactory antioxidant status compared to sedentary students. Based on this conclusion, the widespread use of antioxidant supplements by athletes is questioned.
AFRIKAANSE OPSOMMING: Die menslike liggaam beskik oor ‘n geintegreerde antioksidantmeganisme om dit teen vryradikaalskade te beskerm. Akute oefening kan bydra tot ‘n verhoogde produksie van vry radikale, insluitend reaktiewe suurstofspesies, wat kan veroorsaak dat die antioksidantbeskermingsmeganisme oorlaai word, wat dan kan aanleiding gee tot die ontstaan van oksidatiewe stress. Dit is aangetoon dat persone wat gereeld oefening doen verbeterde antioksidantkapasiteit toon in vergelyking met persone wat geen oefening doen nie. Die resultate van navorsingstudies wat die verband tussen antioksidantkapasiteit en oefening ondersoek is egter teenstrydig en verdere navorsing op hierdie gebied is essensieël om uitsluitsel te kry oor kontensieuse vraagstukke. Die doel van hierdie studie was dus om ondersoek in te stel na die verband tussen plasma antioksidant status, die MnSOD Ala-9Val (-28C T) polimorfisme en geselekteerde plasma antioksidantmerkers in geoefende manlike atlete (rugby spelers) en ‘n onaktiewe manlike kontrolegroep terwyl gekontroleer word vir die dieetinname van die vernaamste antioksidante. Om vir die potensiële invloed van dieetantioksidantinname op die antioksidantstatus van proefpersone in die hoofstudie te kontroleer, is ‘n voedsel frekwensievraelys wat vitamien C-, vitamien E-, karotenoïed- en flavinoïedinname meet, ontwikkel. Die herhaalbaarheid (betroubaarheid) van die vraelys is getoets deur herhaalde voltooiing daarvan deur ‘n toetsgroep (n=38), terwyl die geldighied getoets is deur gebruik te maak van ‘n 28-dag geslote dieetrekord en herhaalde plasma vitamien C bepalings as verwysingswaardes (n=18). Verskeie statistiese toetse is uitgevoer om die frekwensievraelys waardes met die verskillende verwysingswaardes te vergelyk. Alhoewel die Bland -Altman grafieke nie dui op bevredigende herhaalbaarheid en geldigheid van die voedselfrekwensie vraelys nie, dui gelyke gemiddelde waardes, matig tot sterk en betekenisvolle korrelasiekoeffisiënte en ‘n hoë persentasie individue korrek geklassifiseer volgens kwartiele van inname, wel op bevredigende herhaalbaarheid en geldigheid. Matige tot sterk geldigheidskoeffisiënte is ook verkry met die toepassing van “The method of Triads”, wat verdere steun bied vir bevredigende geldigheid. In die hoofstudie is plasma vitamien C, karotenoïedvlakke en totale plasma antioksidantstatus in manlike rugby spelers (n=76) vergelyk met dié van onaktiewe manlike kontroles (n=39). Vergelykings tussen MnSOD genotipes binne die aktiwiteitsgroepe is ook getref. Al genoemde analises is gekontroleer vir dieet antioksidantinname. Resultate dui daarop dat die plasma vitamien C en karotenoïedvlakke van rugby spelers betekenisvol hoër was as dié van die kontrolegroep, wat dui op ‘n meer bevredigende antioksidantstatus. Hierdie resultaat is ook weerspieël in die feit dat totale plasma antioksidantstatus (ORAC) in die rugby spelers oog geneig was om hoër te wees as dié van die kontrole groep. Dit het ook geblyk dat MnSOD genotipe nie ‘n effek gehad het op plasma vitamien C-, karotenoïed- of totale antioksidantstatus nie, met of sonder kontrole vir dieet antioksidantinname. Die dieet vitamien C-, vitamien E-, karotenoïed- en flavinoïedinname (vanaf voedsel en supplemente) was dieselfde vir rugby spelers en kontrole en was toereikend vir beide groepe. Dit blyk dus dat dat die verband tussen antioksidantstatus en MnSOD genotipe in die twee groepe nie beinvloed is deur antioksidantinname nie. Ten slotte kan die gevolgtrekking gemaak word dat manlike rugby spelers ‘n meer bevredigende antioksidant status het as onaktiwe manlike kontroles. Op grond van hierdie gevolgtrekking word die algemene gebruik van antioksidant supplemente deur atlete bevraagteken.
Libri sul tema "Active oxygen – Physiological effect"
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Krauss, Stephen R. O₂xygen: Nature's most important dietary supplement. Kearney, NE: Morris Pub., 1999.
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Grisham, Matthew B. Reactive metabolites of oxygen and nitrogen in biology and medicine. Austin: R.G. Landes, 1992.
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K, Singal Pawan, a cura di. Oxygen radicals in the pathophysiology of heart disease. Boston: Kluwer Academic Publishers, 1988.
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N, Smirnoff, a cura di. Antioxidants and reactive oxygen species in plants. Oxford, UK: Blackwell Pub., 2005.
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Elstner, Erich. Der Sauerstoff: Biochemie, Biologie, Medizin. Mannheim: BI-Wissenschaftsverlag, 1990.
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Gupta, S. Dutta. Reactive oxygen species and antioxidants in higher plants. Enfield, NH: Science Publishers, 2010.
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G, Simic Michael, a cura di. Oxygen radicals in biology and medicine. New York: Plenum Press, 1988.
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Frontiers in Basic Sciences That Relate to Heart, Lung, and Blood Diseases Symposium (8th 1986 Warren Grant Magnuson Clinical Center). Oxygen free radicals: Summary of Frontiers in Basic Sciences That Relate to Heart, Lung, and Blood Diseases Symposium : December 10-12, 1986, Masur Auditorium, Warren Grant Magnuson Clinical Center, National Institutes of Health : administrative report. [Bethesda, Md.?: The Institute, 1987.
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Barry, Halliwell, e Aruoma Okezie I. 1951-, a cura di. DNA and free radicals. New York: Ellis Horwood, 1993.
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Agricultural and Food Chemistry Division of the American Chemical Society Symposium on Antioxidant Nutrients and the Immune Response (1988 Los Angeles, Calif.). Antioxidant nutrients and immune functions. New York: Plenum Press, 1990.
Cerca il testo completoCapitoli di libri sul tema "Active oxygen – Physiological effect"
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Pohlmann, Andreas, Kaixuan Zhao, Sean B. Fain, Pottumarthi V. Prasad e Thoralf Niendorf. "Experimental Protocol for MRI Mapping of the Blood Oxygenation-Sensitive Parameters T2* and T2 in the Kidney". In Methods in Molecular Biology, 403–17. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-0978-1_23.
Testo completoAbstract (sommario):
AbstractRenal hypoxia is generally accepted as a key pathophysiologic event in acute kidney injury of various origins, and has also been suggested to play a role in the development of chronic kidney disease. Here we describe a step-by-step experimental protocol for indirect monitoring of renal blood oxygenation in rodents via the deoxyhemoglobin sensitive MR parameters T2* and T2—a contrast mechanism known as the blood oxygenation level dependent (BOLD) effect. Since an absolute quantification of renal oxygenation from T2*/T2 remains challenging, the effects of controlled and standardized variations in the fraction of inspired oxygen are used for bench marking. This MRI method may be useful for investigating renal blood oxygenation of small rodents in vivo under various experimental (patho)physiological conditions.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This experimental protocol chapter is complemented by two separate chapters describing the basic concept and data analysis.
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Sakamoto, Masako, Kazumasa Aoyagi, Sohji Nagase, Shoji Ohba, Mitsuhiro Miyazaki, Mitsuharu Narita e Shizuo Tojo. "Effect of Active Oxygen on Guanidine Synthesis in Vitro". In Guanidines 2, 87–95. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0821-8_11.
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Hayashi, Nobuya. "Growth Enhancement Effect of Gene Expression of Plants Induced by Active Oxygen Species in Oxygen Plasma". In Agritech: Innovative Agriculture Using Microwaves and Plasmas, 201–25. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-3891-6_12.
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Grinberg, Oleg Y., Minoru Miyake, Huagang Hou, Robert P. Steffen e Harold M. Swartz. "The Dose-Dependent Effect of RSR13, a Synthetic Allosteric Modifier of Hemoglobin, on Physiological Parameters and Brain Tissue Oxygenation in Rats". In Oxygen Transport to Tissue XXIV, 287–96. Boston, MA: Springer US, 2003. http://dx.doi.org/10.1007/978-1-4615-0075-9_27.
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Kobayashi, J., M. Mukaida, Y. Tazoh e S. Miyazawa. "The Effect of Active Atomic Oxygen on Preferential Orientation Axis for YBCO Films". In Advances in Superconductivity VII, 905–8. Tokyo: Springer Japan, 1995. http://dx.doi.org/10.1007/978-4-431-68535-7_204.
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Sheen, L. Y. "Effect of Sulfur-Containing Active Principles in Garlic on the Physiological Function of Hepatocytes". In Animal Cell Technology: Basic & Applied Aspects, 59–63. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-0726-8_11.
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Nemoto, Edwin M., Richard Klementavicius, John A. Melick e Howard Yonas. "Effect of Mild Hypothermia on Active and Basal Cerebral Oxygen Metabolism and Blood Flow". In Advances in Experimental Medicine and Biology, 469–73. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-1875-4_84.
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Chirkov, Yurii G., Oleg V. Korchagin, Vladimir N. Andreev, Vera A. Bogdanovskaya e Viktor I. Rostokin. "Discharge of Lithium–Oxygen Power Source: Effect of Active Layer Thickness and Current Density on Overall Characteristics of Positive Electrode". In Computational Statistics and Mathematical Modeling Methods in Intelligent Systems, 52–69. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-31362-3_7.
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Hadem, Khetbadei Lysinia Hynniewta, Lakhon Kma, Rajeshwar N. Sharan e Arnab Sen. "Anticancer Effect of Aristolochia tagala and Curcuma caesia Acting Through Tumor Necrosis Factor-a". In Handbook of Research on Advanced Phytochemicals and Plant-Based Drug Discovery, 366–94. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-5129-8.ch019.
Testo completoAbstract (sommario):
This chapter begins with a brief description of the events associated with carcinogenesis such as what led a normal cell to transform into a pre-neoplastic one, their multiplication, and development into cancer. The authors also described how reactive oxygen species (ROS) are generated endogenously and from carcinogens, their role in carcinogenesis, and the link between inflammation and cancer. Elucidation of how cancer arises contributes to understanding the molecular mechanisms of action of some natural products. Herbal natural products contain metabolites that exert a physiological action on human body. These metabolites are used therapeutically in modern medical practices to prevent and cure various diseases including cancer. This chapter discusses the anticancer property of two herbal plants Aristolochia tagala Cham. and Curcuma caesia Roxb. in diethylnitrosamine-induced mouse liver cancer and describes the most probable molecular mechanisms of action of the metabolites present in these plants contributing to their anticancer effect.
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Smail, Manal, Sunil Rupee, Khemraj Rupee, Abla Mohammed Ahmed Ismail, Sara Sultan, Frank Christopher Howarth, Ernest A. Adeghate e Jaipaul Singh. "Effects of Diabetes Mellitus on the Conduction System of the Heart: Mini-Review". In New Insights on Cardiomyopathy [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.109423.
Testo completoAbstract (sommario):
Diabetes mellitus can induce substantial damage to the conduction system of the heart, especially the sinoatrial node. This is due to hyperglycemia leading to bradyarrhythmia. DM, via the elevation of HG, generates the production of a number of insulting agents in the myocardium known as reactive oxygen species and reactive carbonyl species, which elicit direct damage to neuro-filament-M and β2-adrenergic receptors in the conducting system as well as a number of cardiac contractile, cation transporting and channel proteins. One cation channel protein is the hyperpolarization-activated cyclic nucleotide-gated potassium channel. It encodes the protein responsible for the hyperpolarizing-activated current or the “funny current” that participates in spontaneous diastolic membrane depolarization in sinoatrial node cells. Gene expression of these proteins and their physiological functions are decreased in the diabetic heart, which affects the generation of electrical impulses or action potentials resulting in increases in RR and PR intervals and QRS complex duration of the electrocardiogram. The heart rate and force of contraction of the myocardium are decreased leading to bradyarrhythmia and sudden cardiac death. This review attempts to explain the cellular mechanism(s) involved in diabetes-induced bradyarrhythmia with emphasis on cation-transporting proteins, especially the hyperpolarization-activated cyclic nucleotide-gated channels pacemaker current channels.
Atti di convegni sul tema "Active oxygen – Physiological effect"
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Liu, Tzu-Ming. "Near Infrared Active Nanomaterials for the Theragnosis of Tumors In Vivo". In JSAP-OSA Joint Symposia. Washington, D.C.: Optica Publishing Group, 2017. http://dx.doi.org/10.1364/jsap.2017.5p_a409_6.
Testo completoAbstract (sommario):
With the engineering of nanomaterials, they become dipolar active to near infrared (NIR) light and form valuable contrasts for deep tissue in vivo imaging at a sub-cellular resolution. The involved physical mechanisms include plasmonic resonance, quantum confinement effects, d-band transition, metal-to-semiconductor transition, bandgap alignment, and lifetime quenching. Some materials can even have multiple contrasts for different molecular imaging modalities like positron emission tomography, magnetic resonance imaging, and computed X-ray tomography. Not only serving as contrast agents in optical microscopy, these materials can also sense the physiological parameters of tumor microenvironment and treat the cancer cells by the photothermal or photodynamic effects. The critical parameters to be sensed include insulin level, oxygen level, and energy metabolism. These NIR imaging tools and molecular probes together provide a theragnosis platform for the study of tumor biology. Especially for the heterogeneous cancer environments, trancing few but important clones like cancer stem cells will be very important for the understanding of their niche environment and the design of targeting therapy. In this presentation, we will show the up-to-date strategies and material systems designed for the theragnosis of tumor. The integrated collaboration among different expertise is required.
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Ley, Obdulia, e Yildiz Bayazitoglu. "Effect of Physiological Parameters on the Temperature Distribution of a Layered Head Model". In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32044.
Testo completoAbstract (sommario):
Brain temperature control is important in clinical therapy, because moderate temperature reduction of brain temperature increases the survival rate after head trauma. A factor that affects the brain temperature distribution is the cerebral blood flow, which is controlled by autoregulatory mechanisms. To improve the existing thermal models of brain, we incorporate the effect of the temperature over the metabolic heat generation, and the regulatory processes that control the cerebral blood perfusion and depend on physiological parameters like, the mean arterial blood pressure, the partial pressure of oxygen, the partial pressure of carbon dioxide, and the cerebral metabolic rate of oxygen consumption. The introduction of these parameters in a thermal model gives information about how specific conditions, such as brain edema, hypoxia, hypercapnia, or hypotension, affect the temperature distribution within the brain. Existing biological thermal models of the human brain, assume constant blood perfusion, and neglect metabolic heat generation or consider it constant, which is a valid assumption for healthy tissue. But during sickness, trauma or under the effect of drugs like anesthetics, the metabolic activity and organ blood flow vary considerably, and such variations must be accounted for in order to achieve accurate thermal modeling. Our work, on a layered head model, shows that variations of the physiological parameters have profound effect on the temperature gradients within the head.
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Che, Meng, Ya Luo, Cong Ge, Ya'Jie Ling, Qin Mo, Shu Luo e Hao'Ru Tang. "Effect of astaxanthin on Strawberry Seedlings under low temperature stress on active oxygen metabolism". In 2017 3rd International Forum on Energy, Environment Science and Materials (IFEESM 2017). Paris, France: Atlantis Press, 2018. http://dx.doi.org/10.2991/ifeesm-17.2018.384.
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de Vries, Heder, Soephie Coenen, Frouke Kingma, Leo Heunks e Angelique De Man. "The effect of oxygen on the PaO2/FiO2-ratio and shunt fraction in patients on mechanical ventilation: a physiological study". In ERS International Congress 2020 abstracts. European Respiratory Society, 2020. http://dx.doi.org/10.1183/13993003.congress-2020.351.
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QIN, Lang, e Jin YIN. "Physiological and Biochemical Effect of Endurance Training of Altitude Training on Fixed Maximal Oxygen Expenditure in Middle and Long Distance Runners". In 2nd International Conference on Biomedical and Biological Engineering 2017 (BBE 2017). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/bbe-17.2017.50.
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Wai, Htet Su, Testsuya Ueda e Chaoyang Li. "Oxygen Ratio Effect on Zinc Oxide Films Fabricated by Radio Frequency Magnetron Sputtering for Photoluminescence Type Gas Sensor Application". In 2021 28th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD). IEEE, 2021. http://dx.doi.org/10.23919/am-fpd52126.2021.9499209.
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Madhusweta Das e P K NAMITHA. "Effect of Incorporation of Antioxidant/Oxygen Scavenger in Self-Supported Potato Starch Based Active Packaging Film on Storability of Some Foods". In 2009 Reno, Nevada, June 21 - June 24, 2009. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2009. http://dx.doi.org/10.13031/2013.26964.
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Frotscher, M., M. Kiekbusch, S. Mews, A. Knopp e D. Serowietzki. "Influence of Active Af on the Fatigue Performance of Peripheral Stents Subjected to Physiological Loading Conditions". In SMST2022. ASM International, 2022. http://dx.doi.org/10.31399/asm.cp.smst2022p0043.
Testo completoAbstract (sommario):
Abstract The temperature difference between active austenite finish temperature, Af, and the intended operating temperature in the range of 3.2 °C to 20.8 °C. has been reported to have an influence on the fatigue lifetime of a pseudoelastic shape-memory device. The negative effect on fatigue life increases with the temperature difference between active Af and, in case of a biomedical device, 37 °C body temperature. In this study, samples were prepared and processed in a manner to replicate aspects of the complex manufacturing process, device design, and geometry of state-of-the-art stents, and physiological loading conditions. Following explantation from the mock vessels after fatigue testing, the stents were inspected using optical microscopy to detect and document the location and number of strut fractures. The fatigue results were compared and assessed for statistical significance between the groups with various active Af temperatures. The variations in the heat treatments, as part of the manufacturing process, resulted in three distinct groups of samples with varying target active Af temperatures. These variances corresponded to differences in fatigue damage.
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Smolensky, A. V., A. B. Miroshnikov, A. D. Formenov e A. G. Antonov. "EFFECT OF THERMAL STRESS ON THE PHYSICAL QUALITY OF TRAINED MEN: PILOT STUDY". In Х Всероссийская научно-практическая конференция. Nizhnevartovsk State University, 2021. http://dx.doi.org/10.36906/fks-2020/57.
Testo completoAbstract (sommario):
The question of the recreational effect of ambient temperature on most of the body's vital processes is often raised, which makes it the most important environmental factor, adaptation to which can be decisive for the body's adaptive capabilities. In our work, we evaluated the effect of using a sauna at + 85°C after tests for maximum performance and physiological characteristics in healthy, physically active men.
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Premasiri, A., G. Happawana e A. Rosen. "Porous Media Tumor Model for Light Penetration and Oxygen Diffusion During Photodynamic Therapy". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66480.
Testo completoAbstract (sommario):
Photodynamic therapy (PDT) is an FDA approved, effective, and minimally invasive cancer treatment modality with few side effects. PDT requires three major components; photosensitizing agent, activation light, and molecular oxygen. Optimization of PDT for an individual patient requires good therapeutic selectivity and high efficacy, where the design of such an effective protocol is based on the understanding of the interaction of key therapeutic components with tumor tissue. Tumor models expressive of changes during the growth of tumor along with the behavior of PDT components facilitate the above requirement. In this study we have developed a mathematical model considering tumor as a porous medium of solid of and liquid that enables to express characteristics of a growing tumor. The characteristic lengths and the volumes that can be changed in the model represent the dynamic changes during the growth of the tumor. An energy based light transport model is superimposed with the porous media model to yield an analytical equation of light penetration in turbid media. In addition a molecular diffusion model combined with the porous media tumor model provides a second analytical equation yielding molecular oxygen diffusion during PDT. Experimentally available physiological and photophysical data are used to obtain the results from the developed models. The commonly used wavelength for PDT, 635nm and corresponding photophsical parameters for a healthy tissue are used for the calculations. The modeling results reveal an exponential decay of optical power along the direction of light penetration and the characteristic changes in oxygen diffusion during PDT. Further observations include the time dependent changes in photosensitizer photobleaching and the corresponding increase in oxygen diffusion length. The modeling results in both cases show a promising accordance with the available experimental results in literature. The model calculations also reveal the effect of light penetration on oxygen diffusion in PDT milieu adding to the expression of its usefulness.
Rapporti di organizzazioni sul tema "Active oxygen – Physiological effect"
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Pesis, Edna, Elizabeth J. Mitcham, Susan E. Ebeler e Amnon Lers. Application of Pre-storage Short Anaerobiosis to Alleviate Superficial Scald and Bitter Pit in Granny Smith Apples. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7593394.bard.
Testo completoAbstract (sommario):
There is increased demand for high quality fruit produced and marketed with reduced chemical inputs to minimize toxic effects on human health and the environment. Granny Smith (GS) apple quality is reduced by two major physiological disorders, superficial scald and bitter pit (BP). These disorders cause great loss to apple growers worldwide. Superficial scald is commonly controlled by chemical treatments, mainly the antioxidant diphenylamine (DPA) and/or the ethylene action inhibitor, 1-methylcyclopropene (1–MCP). Both chemicals are ineffective in controlling bitter pit incidence. We proposed to investigate the beneficial use of non-chemical, abiotic stress with low O2 (LO2) applied for 10d at 20°C on GS apple fruit. During the project we expanded the treatment to more apple cultivars, Golden Delicious (GD) and Starking Delicious (SD) and another pome fruit, the pear. Apple and pear have similar physiological disorders that develop during cold storage and we examined if the LO2 treatment would also be effective on pear. Application of 0.5% LO2 atmosphere for 10d at 20°C or 500ppb 1-MCP at 20°C prior to cold storage at 0°C, was effective in reducing superficial scald in GS apple. Moreover, LO2 pretreatment was also effective in reducing bitter pit (BP) development in California GS and Israeli GD and SD apples The BP symptoms in GS from California were much more prominent, so the effect of LO2 was more dramatic than the effect on the Israeli cvs. GD and SD, nevertheless the LO2 treatment showed the same trend in all cultivars in reducing BP. The LO2 and 1-MCP -treated fruit exhibited lower levels of ethylene, - farnesene and its oxidation product, 6-methyl-5-hepten-2-one (MHO), as determined by SPME/GC-MS analysis. In addition, LO2 pretreatment applied to California Bartlett or Israeli Spadona pears was effective in reducing superficial scald, senescent scald and internal breakdown after 4 m of cold storage at 0°C. For GS apple, low-temperature storage resulted in oxidative stress and chilling injury, caused by increased production of superoxide anions which in turn led to the generation of other dangerous reactive oxygen species (ROS). Using confocal laser-scanning microscopy and H2O2 measurements of apple peel, we observed ROS accumulation in control fruit, while negligible amounts were found in LO2 and 1-MCP treated fruit. Gene-expression levels of ROS-scavenging enzymes were induced by the various pretreatments: catalase was induced by LO2 treatment, whereas Mn superoxide dismutase was induced by 1-MCP treatment. We assume that LO2 and 1-MCP pretreated fruit remained healthier due to reduced production of ethylene and reactive oxygen substances, such as MHO, during cold storage. The LO2-treated apple exhibited greener peel and firmer fruit after 6 m of cold storage, and the fruit had high crispiness leading to high taste preference. In both pear cultivars, the LO2 treatment led to a reduction in internal breakdown and browning around the seed cavity. We tested the LO2 pre-storage treatment on a semi-commercial scale that would be applicable to a small organic grower by sealing the fruit within the plastic field bins. The treatment was most effective with a continuous flow of nitrogen through the bins; however, a single 6 hour flush of nitrogen was also fairly effective. In addition, we determined that it was very important to have the oxygen levels below 0.5% for approximately 10 days to achieve good scald control, not counting the time required to reduce the oxygen concentration. Our LO2 technology has been proven in this project to be effective in reducing several physiological disorders developed in pome fruit during cold storage. We hope that our non-chemical treatment which is friendly to the environment will be used in the near future for the organic apple and pear industry. The next step should be an analysis of the cost-benefits and commercial feasibility.
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Prusky, Dov, Lisa Vaillancourt e Robert Fluhr. Host Ammonification by Postharvest Pathogens and its Contribution to Fungal Colonization and Symptom Development. United States Department of Agriculture, dicembre 2006. http://dx.doi.org/10.32747/2006.7592640.bard.
Testo completoAbstract (sommario):
Postharvest decay of fruits and vegetables caused by pathogenic and saprophytic fungi significantly impairs the quality and quantity of fresh produce brought to market. Consequently, there is considerable interest in identifying factors that determine the susceptibility of these commodities to pathogen infection. Insidious postharvest decays remain quiescent during fruit growth and harvest, but activate during the postharvest period. A key response to the physiological changes occurring during fruit ripening is the initiation of ammonium secretion by the pathogen. Ammonium ions at the infection site (ammonification) have subsequent effects on both the pathogen and the host. An accompanying alkalinization process resulting from ammonia accumulation contributes to pathogenicity, since some important fungal virulence factors, (such as pectate lyase in Colletotrichum sp.), are significantly expressed only under alkaline conditions. In this proposal, investigated the mechanisms by which ammonification and alkalinization of infected tissues by the pathogen affect the host’s defense response to fungal attack, and instead increase compatibility during postharvest pathogen-host interactions. Our hypotheses were:1) that host signals, including ripening-related changes, induce secretion of ammonia by the pathogen; 2) that ammonia accumulation, and the resultant environmental alkalinization regulate the expression of fungal virulence genes that are essential for postharvest rot development; 3) that ammonification enhanced fungal colonization, by “suppression of host responses”, including production of reactive oxygen species, activation of superoxide, and polyphenol oxidase production. Our objectives were: to analyze: 1) factor(s) which activate the production and secretion of ammonia by the fungus; 2) fungal gene(s) that play role(s) in the ammonification process; 3) the relationship between ammonification and the activation of host defense response(s) during pathogen colonization; and 4) analyze hostgene expression in alkalinized regions of fruits attacked by hemibiotrophic fungi.
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Elmann, Anat, Orly Lazarov, Joel Kashman e Rivka Ofir. therapeutic potential of a desert plant and its active compounds for Alzheimer's Disease. United States Department of Agriculture, marzo 2015. http://dx.doi.org/10.32747/2015.7597913.bard.
Testo completoAbstract (sommario):
We chose to focus our investigations on the effect of the active forms, TTF and AcA, rather than the whole (crude) extract. 1. To establish cultivation program designed to develop lead cultivar/s (which will be selected from the different Af accessions) with the highest yield of the active compounds TTF and/or achillolide A (AcA). These cultivar/s will be the source for the purification of large amounts of the active compounds when needed in the future for functional foods/drug development. This task was completed. 2. To determine the effect of the Af extract, TTF and AcA on neuronal vulnerability to oxidative stress in cultured neurons expressing FAD-linked mutants.Compounds were tested in N2a neuroblastoma cell line. In addition, we have tested the effects of TTF and AcA on signaling events promoted by H₂O₂ in astrocytes and by β-amyloid in neuronal N2a cells. 3. To determine the effect of the Af extract, TTF and AcA on neuropathology (amyloidosis and tau phosphorylation) in cultured neurons expressing FAD-linked mutants. 4. To determine the effect of A¦ extract, AcA and TTF on FAD-linked neuropathology (amyloidosis, tau phosphorylation and inflammation) in transgenic mice. 5. To examine whether A¦ extract, TTF and AcA can reverse behavioral deficits in APPswe/PS1DE9 mice, and affect learning and memory and cognitive performance in these FAD-linked transgenic mice. Background to the topic.Neuroinflammation, oxidative stress, glutamate toxicity and amyloid beta (Ab) toxicity are involved in the pathogenesis of Alzheimer's diseases. We have previously purified from Achilleafragrantissimatwo active compounds: a protective flavonoid named 3,5,4’-trihydroxy-6,7,3’-trimethoxyflavone (TTF, Fl-72/2) and an anti-inflammatory sesquiterpenelactone named achillolide A (AcA). Major conclusions, solutions, achievements. In this study we could show that TTF and AcA protected cultured astrocytes from H₂O₂ –induced cell death via interference with cell signaling events. TTF inhibited SAPK/JNK, ERK1/2, MEK1 and CREBphosphorylation, while AcA inhibited only ERK1/2 and MEK1 phosphorylation. In addition to its protective activities, TTF had also anti-inflammatory activities, and inhibited the LPS-elicited secretion of the proinflammatorycytokinesInterleukin 6 (IL-6) and IL-1b from cultured microglial cells. Moreover, TTF and AcA protected neuronal cells from glutamate and Abcytotoxicity by reducing the glutamate and amyloid beta induced levels of intracellular reactive oxygen species (ROS) and via interference with cell signaling events induced by Ab. These compounds also reduced amyloid precursor protein net processing in vitro and in vivo in a mouse model for Alzheimer’s disease and improvedperformance in the novel object recognition learning and memory task. Conclusion: TTF and AcA are potential candidates to be developed as drugs or food additives to prevent, postpone or ameliorate Alzheimer’s disease. Implications, both scientific and agricultural.The synthesis ofAcA and TTF is very complicated. Thus, the plant itself will be the source for the isolation of these compounds or their precursors for synthesis. Therefore, Achilleafragrantissima could be developed into a new crop with industrial potential for the Arava-Negev area in Israel, and will generate more working places in this region.
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Rafaeli, Ada, e Russell Jurenka. Molecular Characterization of PBAN G-protein Coupled Receptors in Moth Pest Species: Design of Antagonists. United States Department of Agriculture, dicembre 2012. http://dx.doi.org/10.32747/2012.7593390.bard.
Testo completoAbstract (sommario):
The proposed research was directed at determining the activation/binding domains and gene regulation of the PBAN-R’s thereby providing information for the design and screening of potential PBAN-R-blockers and to indicate possible ways of preventing the process from proceeding to its completion. Our specific aims included: (1) The identification of the PBAN-R binding domain by a combination of: (a) in silico modeling studies for identifying specific amino-acid side chains that are likely to be involved in binding PBAN with the receptor and; (b) bioassays to verify the modeling studies using mutant receptors, cell lines and pheromone glands (at tissue and organism levels) against selected, designed compounds to confirm if compounds are agonists or antagonists. (2) The elucidation ofthemolecular regulationmechanisms of PBAN-R by:(a) age-dependence of gene expression; (b) the effect of hormones and; (c) PBAN-R characterization in male hair-pencil complexes. Background to the topic Insects have several closely related G protein-coupled receptors (GPCRs) belonging to the pyrokinin/PBAN family, one with the ligand pheromone biosynthesis activating neuropeptide or pyrokinin-2 and another with diapause hormone or pyrokinin-1 as a ligand. We were unable to identify the diapause hormone receptor from Helicoverpa zea despite considerable effort. A third, related receptor is activated by a product of the capa gene, periviscerokinins. The pyrokinin/PBAN family of GPCRs and their ligands has been identified in various insects, such as Drosophila, several moth species, mosquitoes, Triboliumcastaneum, Apis mellifera, Nasoniavitripennis, and Acyrthosiphon pisum. Physiological functions of pyrokinin peptides include muscle contraction, whereas PBAN regulates pheromone production in moths plus other functions indicating the pleiotropic nature of these ligands. Based on the alignment of annotated genomic sequences, the primary and secondary structures of the pyrokinin/PBAN family of receptors have similarity with the corresponding structures of the capa or periviscerokinin receptors of insects and the neuromedin U receptors found in vertebrates. Major conclusions, solutions, achievements Evolutionary trace analysisof receptor extracellular domains exhibited several class-specific amino acid residues, which could indicate putative domains for activation of these receptors by ligand recognition and binding. Through site-directed point mutations, the 3rd extracellular domain of PBAN-R was shown to be critical for ligand selection. We identified three receptors that belong to the PBAN family of GPCRs and a partial sequence for the periviscerokinin receptor from the European corn borer, Ostrinianubilalis. Functional expression studies confirmed that only the C-variant of the PBAN-R is active. We identified a non-peptide agonist that will activate the PBAN-receptor from H. zea. We determined that there is transcriptional control of the PBAN-R in two moth species during the development of the pupa to adult, and we demonstrated that this transcriptional regulation is independent of juvenile hormone biosynthesis. This transcriptional control also occurs in male hair-pencil gland complexes of both moth species indicating a regulatory role for PBAN in males. Ultimate confirmation for PBAN's function in the male tissue was revealed through knockdown of the PBAN-R using RNAi-mediated gene-silencing. Implications, both scientific and agricultural The identification of a non-peptide agonist can be exploited in the future for the design of additional compounds that will activate the receptor and to elucidate the binding properties of this receptor. The increase in expression levels of the PBAN-R transcript was delineated to occur at a critical period of 5 hours post-eclosion and its regulation can now be studied. The mysterious role of PBAN in the males was elucidated by using a combination of physiological, biochemical and molecular genetics techniques.
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Brosh, Arieh, David Robertshaw, Yoav Aharoni, Zvi Holzer, Mario Gutman e Amichai Arieli. Estimation of Energy Expenditure of Free Living and Growing Domesticated Ruminants by Heart Rate Measurement. United States Department of Agriculture, aprile 2002. http://dx.doi.org/10.32747/2002.7580685.bard.
Testo completoAbstract (sommario):
Research objectives were: 1) To study the effect of diet energy density, level of exercise, thermal conditions and reproductive state on cardiovascular function as it relates to oxygen (O2) mobilization. 2) To validate the use of heart rate (HR) to predict energy expenditure (EE) of ruminants, by measuring and calculating the energy balance components at different productive and reproductive states. 3) To validate the use of HR to identify changes in the metabolizable energy (ME) and ME intake (MEI) of grazing ruminants. Background: The development of an effective method for the measurement of EE is essential for understanding the management of both grazing and confined feedlot animals. The use of HR as a method of estimating EE in free-ranging large ruminants has been limited by the availability of suitable field monitoring equipment and by the absence of empirical understanding of the relationship between cardiac function and metabolic rate. Recent developments in microelectronics provide a good opportunity to use small HR devices to monitor free-range animals. The estimation of O2 uptake (VO2) of animals from their HR has to be based upon a consistent relationship between HR and VO2. The question as to whether, or to what extent, feeding level, environmental conditions and reproductive state affect such a relationship is still unanswered. Studies on the basic physiology of O2 mobilization (in USA) and field and feedlot-based investigations (in Israel) covered a , variety of conditions in order to investigate the possibilities of using HR to estimate EE. In USA the physiological studies conducted using animals with implanted flow probes, show that: I) although stroke volume decreases during intense exercise, VO2 per one heart beat per kgBW0.75 (O2 Pulse, O2P) actually increases and measurement of EE by HR and constant O2P may underestimate VO2unless the slope of the regression relating to heart rate and VO2 is also determined, 2) alterations in VO2 associated with the level of feeding and the effects of feeding itself have no effect on O2P, 3) both pregnancy and lactation may increase blood volume, especially lactation; but they have no effect on O2P, 4) ambient temperature in the range of 15 to 25°C in the resting animal has no effect on O2P, and 5) severe heat stress, induced by exercise, elevates body temperature to a sufficient extent that 14% of cardiac output may be required to dissipate the heat generated by exercise rather than for O2 transport. However, this is an unusual situation and its affect on EE estimation in a freely grazing animal, especially when heart rate is monitored over several days, is minor. In Israel three experiments were carried out in the hot summer to define changes in O2P attributable to changes in the time of day or In the heat load. The animals used were lambs and young calves in the growing phase and highly yielding dairy cows. In the growing animals the time of day, or the heat load, affected HR and VO2, but had no effect on O2P. On the other hand, the O2P measured in lactating cows was affected by the heat load; this is similar to the finding in the USA study of sheep. Energy balance trials were conducted to compare MEI recovery by the retained energy (RE) and by EE as measured by HR and O2P. The trial hypothesis was that if HR reliably estimated EE, the MEI proportion to (EE+RE) would not be significantly different from 1.0. Beef cows along a year of their reproductive cycle and growing lambs were used. The MEI recoveries of both trials were not significantly different from 1.0, 1.062+0.026 and 0.957+0.024 respectively. The cows' reproductive state did not affect the O2P, which is similar to the finding in the USA study. Pasture ME content and animal variables such as HR, VO2, O2P and EE of cows on grazing and in confinement were measured throughout three years under twenty-nine combinations of herbage quality and cows' reproductive state. In twelve grazing states, individual faecal output (FO) was measured and MEI was calculated. Regression analyses of the EE and RE dependent on MEI were highly significant (P<0.001). The predicted values of EE at zero intake (78 kcal/kgBW0.75), were similar to those estimated by NRC (1984). The EE at maintenance condition of the grazing cows (EE=MEI, 125 kcal/kgBW0.75) which are in the range of 96.1 to 125.5 as presented by NRC (1996 pp 6-7) for beef cows. Average daily HR and EE were significantly increased by lactation, P<0.001 and P<0.02 respectively. Grazing ME significantly increased HR and EE, P<0.001 and P<0.00l respectively. In contradiction to the finding in confined ewes and cows, the O2P of the grazing cows was significantly affected by the combined treatments (P<0.00l ); this effect was significantly related to the diet ME (P<0.00l ) and consequently to the MEI (P<0.03). Grazing significantly increased O2P compared to confinement. So, when EE of grazing animals during a certain season of the year is estimated using the HR method, the O2P must be re measured whenever grazing ME changes. A high correlation (R2>0.96) of group average EE and of HR dependency on MEI was also found in confined cows, which were fed six different diets and in growing lambs on three diets. In conclusion, the studies conducted in USA and in Israel investigated in depth the physiological mechanisms of cardiovascular and O2 mobilization, and went on to investigate a wide variety of ruminant species, ages, reproductive states, diets ME, time of intake and time of day, and compared these variables under grazing and confinement conditions. From these combined studies we can conclude that EE can be determined from HR measurements during several days, multiplied by O2P measured over a short period of time (10-15 min). The study showed that RE could be determined during the growing phase without slaughtering. In the near future the development microelectronic devices will enable wide use of the HR method to determine EE and energy balance. It will open new scopes of physiological and agricultural research with minimizes strain on animals. The method also has a high potential as a tool for herd management.
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Wideman, Jr., Robert F., Nicholas B. Anthony, Avigdor Cahaner, Alan Shlosberg, Michel Bellaiche e William B. Roush. Integrated Approach to Evaluating Inherited Predictors of Resistance to Pulmonary Hypertension Syndrome (Ascites) in Fast Growing Broiler Chickens. United States Department of Agriculture, dicembre 2000. http://dx.doi.org/10.32747/2000.7575287.bard.
Testo completoAbstract (sommario):
Background PHS (pulmonary hypertension syndrome, ascites syndrome) is a serious cause of loss in the broiler industry, and is a prime example of an undesirable side effect of successful genetic development that may be deleteriously manifested by factors in the environment of growing broilers. Basically, continuous and pinpointed selection for rapid growth in broilers has led to higher oxygen demand and consequently to more frequent manifestation of an inherent potential cardiopulmonary incapability to sufficiently oxygenate the arterial blood. The multifaceted causes and modifiers of PHS make research into finding solutions to the syndrome a complex and multi threaded challenge. This research used several directions to better understand the development of PHS and to probe possible means of achieving a goal of monitoring and increasing resistance to the syndrome. Research Objectives (1) To evaluate the growth dynamics of individuals within breeding stocks and their correlation with individual susceptibility or resistance to PHS; (2) To compile data on diagnostic indices found in this work to be predictive for PHS, during exposure to experimental protocols known to trigger PHS; (3) To conduct detailed physiological evaluations of cardiopulmonary function in broilers; (4) To compile data on growth dynamics and other diagnostic indices in existing lines selected for susceptibility or resistance to PHS; (5) To integrate growth dynamics and other diagnostic data within appropriate statistical procedures to provide geneticists with predictive indices that characterize resistance or susceptibility to PHS. Revisions In the first year, the US team acquired the costly Peckode weigh platform / individual bird I.D. system that was to provide the continuous (several times each day), automated weighing of birds, for a comprehensive monitoring of growth dynamics. However, data generated were found to be inaccurate and irreproducible, so making its use implausible. Henceforth, weighing was manual, this highly labor intensive work precluding some of the original objectives of using such a strategy of growth dynamics in selection procedures involving thousands of birds. Major conclusions, solutions, achievements 1. Healthy broilers were found to have greater oscillations in growth velocity and acceleration than PHS susceptible birds. This proved the scientific validity of our original hypothesis that such differences occur. 2. Growth rate in the first week is higher in PHS-susceptible than in PHS-resistant chicks. Artificial neural network accurately distinguished differences between the two groups based on growth patterns in this period. 3. In the US, the unilateral pulmonary occlusion technique was used in collaboration with a major broiler breeding company to create a commercial broiler line that is highly resistant to PHS induced by fast growth and low ambient temperatures. 4. In Israel, lines were obtained by genetic selection on PHS mortality after cold exposure in a dam-line population comprising of 85 sire families. The wide range of PHS incidence per family (0-50%), high heritability (about 0.6), and the results in cold challenged progeny, suggested a highly effective and relatively easy means for selection for PHS resistance 5. The best minimally-invasive diagnostic indices for prediction of PHS resistance were found to be oximetry, hematocrit values, heart rate and electrocardiographic (ECG) lead II waves. Some differences in results were found between the US and Israeli teams, probably reflecting genetic differences in the broiler strains used in the two countries. For instance the US team found the S wave amplitude to predict PHS susceptibility well, whereas the Israeli team found the P wave amplitude to be a better valid predictor. 6. Comprehensive physiological studies further increased knowledge on the development of PHS cardiopulmonary characteristics of pre-ascitic birds, pulmonary arterial wedge pressures, hypotension/kidney response, pulmonary hemodynamic responses to vasoactive mediators were all examined in depth. Implications, scientific and agricultural Substantial progress has been made in understanding the genetic and environmental factors involved in PHS, and their interaction. The two teams each successfully developed different selection programs, by surgical means and by divergent selection under cold challenge. Monitoring of the progress and success of the programs was done be using the in-depth estimations that this research engendered on the reliability and value of non-invasive predictive parameters. These findings helped corroborate the validity of practical means to improve PHT resistance by research-based programs of selection.
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Yahav, Shlomo, John Brake e Orna Halevy. Pre-natal Epigenetic Adaptation to Improve Thermotolerance Acquisition and Performance of Fast-growing Meat-type Chickens. United States Department of Agriculture, settembre 2009. http://dx.doi.org/10.32747/2009.7592120.bard.
Testo completoAbstract (sommario):
: The necessity to improve broiler thermotolerance and performance led to the following hypothesis: (a) thethermoregulatory-response threshold for heat production can be altered by thermal manipulation (TM) during incubation so as to improve the acquisition of thermotolerance in the post-hatch broiler;and (b) TM during embryogenesis will improve myoblast proliferation during the embryonic and post-hatch periods with subsequent enhanced muscle growth and meat production. The original objectives of this study were as follow: 1. to assess the timing, temperature, duration, and turning frequency required for optimal TM during embryogenesis; 2. to evaluate the effect of TM during embryogenesis on thermoregulation (heat production and heat dissipation) during four phases: (1) embryogenesis, (2) at hatch, (3) during growth, and (4) during heat challenge near marketing age; 3. to investigate the stimulatory effect of thermotolerance on hormones that regulate thermogenesis and stress (T₄, T₃, corticosterone, glucagon); 4. to determine the effect of TM on performance (BW gain, feed intake, feed efficiency, carcass yield, breast muscle yield) of broiler chickens; and 5. to study the effect of TM during embryogenesis on skeletal muscle growth, including myoblast proliferation and fiber development, in the embryo and post-hatch chicks.This study has achieved all the original objectives. Only the plasma glucagon concentration (objective 3) was not measured as a result of technical obstacles. Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” In order to sustain or even improve broiler performance, TM during the period of embryogenesis when satellite cell population normally expand should increase absolute pectoralis muscle weight in broilers post-hatch. Major conclusions: Intermittent TM (39.5°C for 12 h/day) during embryogenesis when the thyroid and adrenal axis was developing and maturing (E7 to E16 inclusive) had a long lasting thermoregulatory effect that improved thermotolerance of broiler chickens exposed to acute thermal stress at market age by lowering their functional Tb set point, thus lowering metabolic rate at hatch, improving sensible heat loss, and significantly decreasing the level of stress. Increased machine ventilation rate was required during TM so as to supply the oxygen required for the periods of increased embryonic development. Enhancing embryonic development was found to be accomplished by a combination of pre-incubation heating of embryos for 12 h at 30°C, followed by increasing incubation temperature to 38°C during the first 3 days of incubation. It was further facilitated by increasing turning frequency of the eggs to 48 or 96 times daily. TM during critical phases of muscle development in the late-term chick embryo (E16 to E18) for 3 or 6 hours (39.5°C) had an immediate stimulatory effect on myoblast proliferation that lasted for up to two weeks post-hatch; this was followed by increased hypertrophy at later ages. The various incubation temperatures and TM durations focused on the fine-tuning of muscle development and growth processes during late-term embryogenesis as well as in post-hatch chickens.
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Uni, Zehava, e Peter Ferket. Enhancement of development of broilers and poults by in ovo feeding. United States Department of Agriculture, maggio 2006. http://dx.doi.org/10.32747/2006.7695878.bard.
Testo completoAbstract (sommario):
The specific objectives of this research were the study of the physical and nutritional properties of the In Ovo Feeding (IOF) solution (i.e. theosmostic properties and the carbohydrate: protein ratio composition). Then, using the optimal solution for determining its effect on hatchability, early nutritional status and intestinal development of broilers and turkey during the last quarter of incubation through to 7 days post-hatch (i.e. pre-post hatch period) by using molecular, biochemical and histological tools. The objective for the last research phase was the determination of the effect of in ovo feeding on growth performance and economically valuable production traits of broiler and turkey flocks reared under practical commercial conditions. The few days before- and- after hatch is a critical period for the development and survival of commercial broilers and turkeys. During this period chicks make the metabolic and physiological transition from egg nutriture (i.e. yolk) to exogenous feed. Late-term embryos and hatchlings may suffer a low glycogen status, especially when oxygen availability to the embryo is limited by low egg conductance or poor incubator ventilation. Much of the glycogen reserve in the late-term chicken embryo is utilized for hatching. Subsequently, the chick must rebuild that glycogen reserve by gluconeogenesis from body protein (mostly from the breast muscle) to support post-hatch thermoregulation and survival until the chicks are able to consume and utilize dietary nutrients. Immediately post-hatch, the chick draws from its limited body reserves and undergoes rapid physical and functional development of the gastrointestinal tract (GIT) in order to digest feed and assimilate nutrients. Because the intestine is the nutrient primary supply organ, the sooner it achieves this functional capacity, the sooner the young bird can utilize dietary nutrients and efficiently grow at its genetic potential and resist infectious and metabolic disease. Feeding the embryo when they consume the amniotic fluid (IOF idea and method) showed accelerated enteric development and elevated capacity to digest nutrients. By injecting a feeding solution into the embryonic amnion, the embryo naturally consume supplemental nutrients orally before hatching. This stimulates intestinal development to start earlier as was exhibited by elevated gene expression of several functional genes (brush border enzymes an transporters , elvated surface area, elevated mucin production . Moreover, supplying supplemental nutrients at a critical developmental stage by this in ovo feeding technology improves the hatchling’s nutritional status. In comparison to controls, administration of 1 ml of in ovo feeding solution, containing dextrin, maltose, sucrose and amino acids, into the amnion of the broiler embryo increased dramatically total liver glycogen in broilers and in turkeys in the pre-hatch period. In addition, an elevated relative breast muscle size (% of broiler BW) was observed in IOF chicks to be 6.5% greater at hatch and 7 days post-hatch in comparison to controls. Experiment have shown that IOF broilers and turkeys increased hatchling weights by 3% to 7% (P<0.05) over non injected controls. These responses depend upon the strain, the breeder hen age and in ovo feed composition. The weight advantage observed during the first week after hatch was found to be sustained at least through 35 days of age. Currently, research is done in order to adopt the knowledge for commercial practice.
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Avni, Adi, e Gitta L. Coaker. Proteomic investigation of a tomato receptor like protein recognizing fungal pathogens. United States Department of Agriculture, gennaio 2015. http://dx.doi.org/10.32747/2015.7600030.bard.
Testo completoAbstract (sommario):
Maximizing food production with minimal negative effects on the environment remains a long-term challenge for sustainable food production. Microbial pathogens cause devastating diseases, minimizing crop losses by controlling plant diseases can contribute significantly to this goal. All plants possess an innate immune system that is activated after recognition of microbial-derived molecules. The fungal protein Eix induces defense responses in tomato and tobacco. Plants recognize Eix through a leucine-rich-repeat receptor- like-protein (LRR-RLP) termed LeEix. Despite the knowledge obtained from studies on tomato, relatively little is known about signaling initiated by RLP-type immune receptors. The focus of this grant proposal is to generate a foundational understanding of how the tomato xylanase receptor LeEix2 signals to confer defense responses. LeEix2 recognition results in pattern triggered immunity (PTI). The grant has two main aims: (1) Isolate the LeEix2 protein complex in an active and resting state; (2) Examine the biological function of the identified proteins in relation to LeEix2 signaling upon perception of the xylanase elicitor Eix. We used two separate approaches to isolate receptor interacting proteins. Transgenic tomato plants expressing LeEix2 fused to the GFP tag were used to identify complex components at a resting and activated state. LeEix2 complexes were purified by mass spectrometry and associated proteins identified by mass spectrometry. We identified novel proteins that interact with LeEix receptor by proteomics analysis. We identified two dynamin related proteins (DRPs), a coiled coil – nucleotide binding site leucine rich repeat (SlNRC4a) protein. In the second approach we used the split ubiquitin yeast two hybrid (Y2H) screen system to identified receptor-like protein kinase At5g24010-like (SlRLK-like) (Solyc01g094920.2.1) as an interactor of LeEIX2. We examined the role of SlNRC4a in plant immunity. Co-immunoprecipitation demonstrates that SlNRC4a is able to associate with different PRRs. Physiological assays with specific elicitors revealed that SlNRC4a generally alters PRR-mediated responses. SlNRC4a overexpression enhances defense responses while silencing SlNRC4 reduces plant immunity. We propose that SlNRC4a acts as a non-canonical positive regulator of immunity mediated by diverse PRRs. Thus, SlNRC4a could link both intracellular and extracellular immune perception. SlDRP2A localizes at the plasma membrane. Overexpression of SlDRP2A increases the sub-population of LeEIX2 inVHAa1 endosomes, and enhances LeEIX2- and FLS2-mediated defense. The effect of SlDRP2A on induction of plant immunity highlights the importance of endomembrane components and endocytosis in signal propagation during plant immune . The interaction of LeEIX2 with SlRLK-like was verified using co- immunoprecipitation and a bimolecular fluorescence complementation assay. The defence responses induced by EIX were markedly reduced when SlRLK-like was over-expressed, and mutation of slrlk-likeusing CRISPR/Cas9 increased EIX- induced ethylene production and SlACSgene expression in tomato. Co-expression of SlRLK-like with different RLPs and RLKs led to their degradation, apparently through an endoplasmic reticulum-associated degradation process. We provided new knowledge and expertise relevant to expression of specific be exploited to enhance immunity in crops enabling the development of novel environmentally friendly disease control strategies.
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Steffens, John C., e Eithan Harel. Polyphenol Oxidases- Expression, Assembly and Function. United States Department of Agriculture, gennaio 1995. http://dx.doi.org/10.32747/1995.7571358.bard.
Testo completoAbstract (sommario):
Polyphenol oxidases (PPOs) participate in the preparation of many plant products on the one hand and cause considerable losses during processing of plant products on the other hand. However, the physiological functions of plant PPO were still a subject of controversy at the onset of the project. Preliminary observations that suggested involvement of PPOs in resistance to herbivores and pathogens held great promise for application in agriculture but required elucidation of PPO's function if modulation of PPO expression is to be considered for improving plant protection or storage and processing of plant products. Suggestions on a possible role of PPO in various aspects of chloroplast metabolism were also relevant in this context. The characterization of plant PPO genes opened a way for achieving these goals. We reasoned that "understanding PPO targeting and routing, designing ways to manipulate its expression and assessing the effects of such modifications will enable determination of the true properties of the enzyme and open the way for controlling its activity". The objective of the project was to "obtain an insight into the function and biological significance of PPOs" by examining possible function(s) of PPO in photosynthesis and plant-pest interactions using transgenic tomato plants; extending our understanding of PPO routing and assembly and the mechanism of its thylakoid translocation; preparing recombinant PPOs for use in import studies, determination of the genuine properties of PPOs and understanding its assembly and determining the effect of PPO's absence on chloroplast performance. Results obtained during work on the project made it necessary to abandon some minor objectives and devote the effort to more promising topics. Such changes are mentioned in the 'Body of the report' which is arranged according to the objectives of the original proposal. The complex expression pattern of tomato PPO gene family was determined. Individual members of the family are differentially expressed in various parts of the plant and subjected to developmentally regulated turnover. Some members are differentially regulated also by pathogens, wounding and chemical wound signals. Wounding systemically induces PPO activity and level in potato. Only tissues that are developmentally competent to express PPO are capable of responding to the systemic wounding signal by increased accumulation of PPO mRNA. Down regulation of PPO genes causes hyper susceptibility to leaf pathogens in tomato while over expression regulation of PPO expression in tomato plants is their apparent increased tolerance to drought. Both the enhanced disease resistance conferred by PPO over expression and the increased stress tolerance due to down regulation can be used in the engineering of improved crop plants. Photosynthesis rate and variable fluorescence measurements in wild type, and PPO-null and over expressing transgenic tomato lines suggest that PPO does not enable plants to cope better with stressful high light intensities or reactive oxygen species. Rather high levels of the enzyme aggravate the damage caused under such conditions. Our work suggests that PPO's primary role is in defending plants against pathogens and herbivores. Jasmonate and ethylene, and apparently also salicylate, signals involved in responses to wounding and defense against herbivores and pathogens, enhance markedly and specifically the competence of chloroplasts to import and process pPPO. The interaction of the precursor with thylakoid membranes is primarily affected. The routing of PPO shows other unusual properties: stromal processing occurs in two sites, resulting in intermediates that are translocated across thylakoids by two different mechanisms - a DpH- and a Sec-dependent one. It is suggested that the dual pattern of processing and routing constitutes a'fail safe' mechanism, reflecting the need for a rapid and flexible response to defense challenges. Many of the observations described above should be taken into consideration when manipulation of PPO expression is contemplated for use in crop improvement.