Home About us Contact
|
Home About us Contact | ||
|
|
||
Base Status (base + status)
Selected AbstractsTemperature-dependent changes in energy metabolism, intracellular pH and blood oxygen tension in the Atlantic codJOURNAL OF FISH BIOLOGY, Issue 6 2003F. J. Sartoris The effect of acute increase in temperature on oxygen partial pressure (Po2) was measured in the gill arches of Atlantic cod Gadus morhua between 10 and 19° C by use of oxygen microoptodes. Oxygen saturation of the gill blood under control conditions varied between 90 and 15% reflecting a variable percentage of arterial or venous blood in accordance with the position of each optode in the gill arch. The data obtained suggested that arterial Po2 remained more or less constant and arterial oxygen uptake did not become limiting during warming. A progressive drop in venous Po2, however, was observed at >10° C indicating that excessive oxygen uptake from the blood is not fully compensated for by circulatory performance, until finally, Po2 levels fully collapse. In a second set of experiments energy and acid,base status of white muscle of Atlantic cod in vivo was measured by magnetic resonance (31P-NMR) spectroscopy in unanaesthetized and unimmobilized fish in the temperature range between 13 and 21° C. A decrease in white muscle intracellular pH (pHi) with temperature occurred between 10 and 16° C (,pH per ° C = ,0ˇ025 per ° C). In white muscle temperature changes had no influence on high-energy phosphates such as phosphocreatine (PCr) or ATP except during exposure to high critical temperatures (>16° C), indicating that white muscle energy status appears to be relatively insensitive to thermal stress if compared to the thermal sensitivity of the whole animal. The data were consistent with the hypothesis of an oxygen limitation of thermal tolerance in animals, which is set by limited capacity of oxygen supply mechanisms. In the case of Atlantic cod circulatory rather than ventilatory performance may be the first process to cause oxygen deficiency during heat stress. [source] Weed vegetation of arable land in Central Europe: Gradients of diversity and species compositionJOURNAL OF VEGETATION SCIENCE, Issue 3 2004Z. Lososová Abstract: Question: What are the main broad-scale spatial and temporal gradients in species composition of arable weed communities and what are their underlying environmental variables? Location: Czech Republic and Slovakia. Methods: A selection of 2653 geographically stratified relevés sampled between 1954,2003 was analysed with direct and indirect ordination, regression analysis and analysis of beta diversity. Results: Major changes in weed species composition were associated with a complex gradient of increasing altitude and precipitation and decreasing temperature and base status of the soils. The proportion of hemicryptophytes increased, therophytes and alien species decreased, species richness increased and beta diversity decreased with increasing altitude. The second most important gradient of weed species composition was associated with seasonal changes, resulting in striking differences between weed communities developed in spring and summer. In summer, weed communities tended to have more neophytes, higher species richness and higher beta diversity. The third gradient reflected long-term changes in weed vegetation over past decades. The proportion of hemicryptophytes and neophytes increased, while therophytes and archaeophytes decreased, as did species richness over time. The fourth gradient was due to crop plants. Cultures whose management involves less disturbances, such as cereals, harboured less geophytes and neophytes, and had higher species richness but lower beta diversity than frequently disturbed cultures, such as root crops. Conclusions: Species composition of Central European weed vegetation is mainly influenced by broad-scale climatic and edaphic factors, but its variations due to seasonal dynamics and long-term changes in agricultural management are also striking. Crop plants and crop-specific management affect it to a lesser, but still significant extent. [source] The influence of crystalloid type on acid,base and electrolyte status of cats with urethral obstructionJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 4 2008DACVECC, DACVIM (Medicine), Kenneth J. Drobatz DVM Abstract Objective: To compare the effect of a balanced isotonic crystalloid solution with that of 0.9% sodium chloride on the acid,base and electrolyte status of cats with urethral obstruction. Design: Randomized prospective clinical trial. Setting: Academic veterinary emergency room. Animals: Sixty-eight cats with naturally occurring urethral obstruction. Interventions: Cats were randomized to receive either a balanced isotonic crystalloid solution (Normosol-R, n=39) or 0.9% sodium chloride (n=29) for fluid therapy. Baseline venous blood gas and blood electrolyte values were obtained at the time of admission and at intervals during the course of therapy. Measurements and main results: Baseline values were similar between groups. Cats receiving Normosol-R had a significantly higher blood pH at 12 hours, a significantly greater increase in blood pH from baseline at 6 and 12 hours, as well as a significantly higher blood bicarbonate concentration at 12 hours and a significantly greater increase in blood bicarbonate from baseline at 6 and 12 hours. Conversely, the increase in blood chloride from baseline was significantly higher at 2, 6, and 12 hours in cats receiving 0.9% sodium chloride. There were no significant differences in the rate of decline of blood potassium from baseline between groups. Subgroup analysis of hyperkalemic cats (K+>6.0 mmol/L) and acidemic cats (pH<7.3) yielded similar findings. Conclusions: While both crystalloid solutions appear safe and effective for fluid therapy in cats with urethral obstruction, the use of a balanced electrolyte solution may allow more rapid correction of blood acid,base status within the first 12 hours of fluid therapy. The use of a potassium-containing balanced electrolyte solution does not appear to affect the rate of normalization of blood potassium in treated cats with urethral obstruction. [source] Acid,base balance in sea bass (Dicentrarchus labrax L.) in relation to water oxygen concentrationAQUACULTURE RESEARCH, Issue 12 2003S Cecchini Abstract The influence of water oxygen concentration on the acid,base balance of sea bass was evaluated. Fish weighing 200,250 g were cultured under different dissolved oxygen concentrations of 64%, 97%, 150% and 250% saturation (92.7, 140.5, 217.5 and 362.7 mmHg respectively) under mild hypoxia, normoxia, mild hyperoxia and high hyperoxia conditions. The results showed that high hyperoxia and mild hypoxia conditions modified some blood parameters significantly when compared with fish held under the normoxia condition, while no differences were shown with respect to the acid,base balance of fish cultured under normoxia and mild hyperoxia conditions. This testifies that the mild hyperoxia condition does not produce physiological disturbances in the acid,base status of sea bass and it could be considered a favourable condition in sea bass land-based farming, mainly in comparison with the mild hypoxia condition, responsible for other physiological problems. [source] Changes in the ST-interval segment of the fetal electrocardiogram in relation to acid,base status at birthBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 13 2008M Melin Objective, To assess the occurrence of ST-interval segment changes of the fetal electrocardiogram (ECG) and cardiotocographic (CTG) abnormalities preceding acidaemia at birth. Design, Case,control study. Setting, University hospital labour ward. Sample, Newborns with severe cord artery metabolic acidaemia (pH < 7.00 and lactate , 10 mmol/l; n= 24), moderate metabolic acidaemia (pH 7.00,7.09 and lactate , 10; n= 48), acidaemia (pH 7.00,7.09; n= 52), pre-acidaemia (pH 7.10,7.19; n= 265), and controls (pH , 7.20; n= 117). Methods, Monitoring traces were assessed blinded to outcome. Main outcome measures, CTG and ST changes. Results, Any ST event occurred significantly more often among cases with severe (79%) and moderate (75%) metabolic acidaemia than among controls (50%). The difference was restricted to baseline T/QRS rises and to the second stage of labour, during which any event only occurred significantly more often among cases with severe metabolic acidaemia (62%) than among controls (38%). ST events coincided with abnormal CTG patterns in 67, 44, 40, and 28% of cases with severe and moderate metabolic acidaemia, acidaemia, and pre-acidaemia, respectively, and in 12% of controls. ST events with intermediary CTG were similarly frequent in the case groups (0,6%) as in the controls (4%). The ST guidelines stated intervention in 96, 62, 73, and 49% of case groups and 23% of controls. Conclusions, Only two of three cases with severe and less than half of cases with moderate metabolic acidaemia were preceded by ST events coinciding with CTG abnormalities. It is therefore important to intervene for long-lasting, rapidly deteriorating or marked (preterminal) CTG abnormalities, also in the absence of ST events. [source] Adaptations Of Skeletal Muscle To Prolonged, Intense Endurance TrainingCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2002John A Hawley SUMMARY 1. Endurance exercise induces a variety of metabolic and morphological responses/adaptations in skeletal muscle that function to minimize cellular disturbances during subsequent training sessions. 2. Chronic adaptations in skeletal muscle are likely to be the result of the cumulative effect of repeated bouts of exercise, with the initial signalling responses leading to such adaptations occurring after each training session. 3. Recently, activation of the mitogen-activated protein kinase signalling cascade has been proposed as a possible mechanism involved in the regulation of many of the exercise-induced adaptations in skeletal muscle. 4. The protein targets of AMP-activated protein kinase also appear to be involved in both the regulation of acute metabolic responses and chronic adaptations to exercise. 5. Endurance training is associated with an increase in the activities of key enzymes of the mitochondrial electron transport chain and a concomitant increase in mitochondrial protein concentration. These morphological changes, along with increased capillary supply, result in a shift in trained muscle to a greater reliance on fat as a fuel with a concomitant reduction in glycolytic flux and tighter control of acid,base status. Taken collectively, these adaptations result in an enhanced performance capacity. [source] | |||||||||||||