Initial Control Values Research Articles

Poređenje dinamičkog modela i kontrole leta plus i unakrsnih kvadkopter konfiguracija

This research investigates and demonstrates the fundamental differences in performance and operation of both the cross and quadcopter configurations. The system's nonlinear dynamic model was first derived and implemented in Simulink for each quadcopter. The identical initial control values were applied for both quadcopters. The plus-configuration creates a yaw moment when a pitch or roll control input is supplied using multi-rotor controls; however, the cross-configuration decouples pitch and roll control from yaw. However, the plus-quad showed considerable instability while rotating with a pitch and rolling due to the self-generated residual rotation of the four rotors, which is small in the cross quadcopter, making it more maneuverability stable. The obtained results showed that both quadcopters consume the same energy amount.

Pulse oximetry and clinical changes during electrosurgery in dogs anaesthetized with Xylazine-Thiopentone and Xylazine-Ketamine combinations

This study was performed to explore the pulse oximetric evaluation of cardio-respiratory systems along with the determination of body temperature in dogs anaesthetized with xylazine-thiopentone (X-T) and xylazine-ketamine (X-K) combinations during electrosurgery. Six apparently healthy dogs weighed 20 to 25 kg undergoing electrosurgery (bipolar), were divided into two groups: group A (X-T) and group B (X-K). In group A (n=3), dogs were anaesthetized with xylazine @ 1.1 mg/kg body weight (BW) as intramuscular (IM) and thiopentone @ 20 mg/kg BW as intravenous (IV) injections, and in group B (n=3), dogs were anaesthetized with xylazine @ 1.1mg/kg BW IM and ketamine @ 5.5 mg/kg BW IM after premedication with atropine sulphate @ 0.05 mg/kg BW IM. Bipolar electrosurgery for gastrotomy or castration was performed in the dogs. Pulse oximetric monitoring and the evaluation of clinical changes: heart rate, respiratory rate and peripheral blood oxygen saturation (SpO2) were done along with the determination of body temperature before the induction of anaesthesia (control) and thereafter on 10, 20, 30, 40 and 50 minutes postinduction in both groups during electrosurgery. Temperature, heart rate and respiratory rate were altered significantly (P<0.05) during the experimental period in both groups as compared to the control values. SpO2 was decreased significantly (P<0.05) throughout the experiment and returned to the level of initial control value after complete recovery in both groups. These findings revealed that during electrosurgery in dogs the anaesthetic combinations of X-T and X-K exert certain clinical changes in the vital signs (body temperature, heart rate, respiratory rate) and SpO2 which should be carefully considered to take necessary steps for perioperative patient’s safety and recovery.
 Res. Agric., Livest. Fish.7(1): 97-105, April 2020

Complex Interaction Between Low-Frequency APD Oscillations and Beat-to-Beat APD Variability in Humans Is Governed by the Sympathetic Nervous System.

BackgroundRecent clinical, experimental and modeling studies link oscillations of ventricular repolarization in the low frequency (LF) (approx. 0.1 Hz) to arrhythmogenesis. Sympathetic provocation has been shown to enhance both LF oscillations of action potential duration (APD) and beat-to-beat variability (BVR) in humans. We hypothesized that beta-adrenergic blockade would reduce LF oscillations of APD and BVR of APD in humans and that the two processes might be linked.Methods and ResultsTwelve patients with normal ventricles were studied during routine electrophysiological procedures. Activation-recovery intervals (ARI) as a conventional surrogate for APD were recorded from 10 left and 10 right ventricular endocardial sites before and after acute beta-adrenergic adrenergic blockade. Cycle length was maintained constant with right ventricular pacing. Oscillatory behavior of ARI was quantified by spectral analysis and BVR as the short-term variability. Beta-adrenergic blockade reduced LF ARI oscillations (8.6 ± 4.5 ms2 vs. 5.5 ± 3.5 ms2, p = 0.027). A significant correlation was present between the initial control values and reduction seen following beta-adrenergic blockade in LF ARI (rs = 0.62, p = 0.037) such that when initial values are high the effect is greater. A similar relationship was also seen in the beat-to beat variability of ARI (rs = 0.74, p = 0.008). There was a significant correlation between the beta-adrenergic blockade induced reduction in LF power of ARI and the witnessed reduction of beat-to-beat variability of ARI (rs = 0.74, p = 0.01). These clinical results accord with recent computational modeling studies which provide mechanistic insight into the interactions of LF oscillations and beat-to-beat variability of APD at the cellular level.ConclusionBeta-adrenergic blockade reduces LF oscillatory behavior of APD (ARI) in humans in vivo. Our results support the importance of LF oscillations in modulating the response of BVR to beta-adrenergic blockers, suggesting that LF oscillations may play role in modulating beta-adrenergic mechanisms underlying BVR.

AN INFLUENCE OF UNITHIOL ON THE FUNCTIONING OF KIDNEY

This work deals with the investigation of an influence of the antidote agent Unithiol(sodium 2,3-dimerkaptopropanesulfonate) on the excretion functioning of kidney atvarious duration of use.Goal of the work - to investigate the way unithiole affects the excretion function ofkidney after the single or prolonged use.Materials and methods. The work was done in the adult male rats after the single, 10 or20 days long use of Unithiole (50 mg/kg subcutaneously) on the background ofadditional water load (forced diuresis) that has been realized through the intragastricwater intake of 5 % of the animal body weight. Then the rat urine was analyzed for thecontent of sodium, potassium and hydrogen ions, creatinin, proteins, ammonium andtitratable acids. The experimental data were compared with the respective initial controlvalues and the values obtained from the previous group of animals. This way, the ionregulating, excretion and acid-adjusting functions of the kidney were analyzed fordifferent regimes of the medicine use.Results. The single injection of the medicine 2 hours after the water load applicationcaused the 11.8 % increase in diuresis, 1.7 times decrease in the sodium concentration inthe urine and the 1.5 time decrease in natriuresis. Since no changes in kaliuresis wereregistered, the sodium/potassium coefficient has decreased 1.6 times. The concentrationand excretion of protein in urine has decreased almost three times on the background ofrather insignificant (12.6 %) increase in the creatinin excretion. No changes wereregistered in the excretion of titratable acids, ammonium and in the value of ammoniumcoefficient. The excretion of hydrogen ions has halved pushing pH towards basic. Incomparison to the control group, the urination volume increased by 15.9 % after the 10and 20 days long use of the medicine. The concentration of sodium in the urine decrease2.7-2.2 times, natriuresis - 2.4 and 1.9 times correspondingly comparing to the respectiveinitial values. The value of kaliuresis has increased 1.3 times after the 20 days long usewhile similarly to the 10 days long experiment, the sodium/potassium coefficient valueremained 12.6 times lower than that in the control group. The protein concentration inthe urine and the level of its excretion decreased 4.3 and 3.6 times correspondingly inrespect to their initial values. The ammonium coefficient value has increased 1.4 times incomparison with the control group. Excretion of the hydrogen ions also increased up tothe control group level resulting in some alkalization of the urine.Conclusions. 1. An influence of Unithiol on the rat kidney functioning (ion-regulating,excretion and acid-adjusting functions) greatly depends on the duration of use. 2. Singleuse of the medicine results in some diuresis increase, alkalization of the urine, significantincrease in the sodium ions and proteins excretion. 3. Prolonged (10 or 20 days long)use of the medicine causes some diuretic effect, retention of protein and sodium on thebackground of some alkalization of the urine.

Metabolomic Investigations of the Temporal Effects of Exposure to Pharmaceuticals and Personal Care Products and Their Mixture in the Eastern Oyster (Crassostrea virginica).

The eastern oyster (Crassostrea virginica) supports a large aquaculture industry and is a keystone species along the Atlantic seaboard. Native oysters are routinely exposed to a complex mixture of contaminants that increasingly includes pharmaceuticals and personal care products (PPCPs). Unfortunately, the biological effects of chemical mixtures on oysters are poorly understood. Untargeted gas chromatography-mass spectrometry metabolomics was utilized to quantify the response of oysters exposed to fluoxetine, N,N-diethyl-meta-toluamide, 17α-ethynylestradiol, diphenhydramine, and their mixture. Oysters were exposed to 1 µg/L of each chemical or mixture for 10 d, followed by an 8-d depuration period. Adductor muscle (n = 14/treatment) was sampled at days 0, 1, 5, 10, and 18. Trajectory analysis illustrated that metabolic effects and class separation of the treatments varied at each time point and that, overall, the oysters were only able to partially recover from these exposures post-depuration. Altered metabolites were associated with cellular energetics (i.e., Krebs cycle intermediates), as well as amino acid metabolism and fatty acids. Exposure to these PPCPs also affected metabolic pathways associated with anaerobic metabolism, osmotic stress, and oxidative stress, in addition to the physiological effects of each chemical's postulated mechanism of action. Following depuration, fewer metabolites were altered, but none of the treatments returned them to their initial control values, indicating that metabolic disruptions were long-lasting. Interestingly, the mixture did not directly cluster with individual treatments in the scores plot from partial least squares discriminant analysis, and many of its affected metabolic pathways were not well predicted from the individual treatments. The present study highlights the utility of untargeted metabolomics in developing exposure biomarkers for compounds with different modes of action in bivalves. Environ Toxicol Chem 2020;39:419-436. © 2019 SETAC.

Gas Exchange in Caryocar Brasiliense Cambess Seedlings in Water Deficit Conditions

Abstract In this study, we assessed the gas exchange in Caryocar brasiliense seedlings in water deficit conditions and their capacity to recover after rehydration. We assessed plant photosynthetic rates, internal carbon concentrations, stomatal conductance, transpiration rates, water-use efficiency, instantaneous carboxylation efficiency, chlorophyll index, and photosystem II quantum efficiency. All gas exchange parameters were reduced after the suspension of irrigation. Seedling photosynthetic rates approached zero after 12 days. The equilibrium was reestablished in all variables 11 days after re-initiating irrigation, with the exception of internal CO2 concentration and stomatal conductance. Exposure of seedlings to water stress resulted in drastically reduced photosynthetic processes. This reduction occurred due to the limitation of stomatal conductance and low rubisco carboxylation efficiency but not to irreversible damage photosystem II. All of these parameters demonstrated recuperation with rehydration, but only the photosynthetic rates reached initial control values.

Potensi Susu Basi menjadi Pupuk Organik dengan Penambahan Larutan Effective Microorganism 4 dan Cocopeat

In the milk, content is strongly associated with nutrients to increase the productivity of crop yields. The rest of the milk that has been consumed so far has only been wasted. This requires new innovations in the manufacture of organic fertilizer products. The purpose of this study was to determine the best composition comparison between stale milk, EM4 solution and cocopeat in the process of making liquid and solid organic fertilizer and determine the c-organic value, N total, total P2O5, K2O total, and pH value. Initial analysis of liquid organic fertilizer obtained pH values of 5.10, total P2O5 of 0.342% and total nitrogen of 0.569% at initial control (stale milk only) and final values of 1.010% of total P2O5, 1.113% of total nitrogen and 10.480% of organic carbon in R3 ( 30: 5: 1). Initial analysis of solid organic fertilizer obtained pH values 5.26%, 2.668% total P2O5, 0.952% K2O total and 2.780% N total at R1 (10: 5: 1) and final values obtained 1.578% P2O5total at R1 (10: 5: 1) , 2.937% N total in R2 and 43.912% c-organic in R3. This shows that stale milk with the addition of EM4 and cocopeat solutions has an effect on phosphorus and nitrogen nutrients in liquid and solid organic fertilizer.

Rate optimization of fractional flow reservoir model based on the continuous adjoint method

In this paper, continuous adjoint method is applied to research the rate optimization of fractional flow reservoir model. The continuous adjoint equations are derived by the variational theory and the stable numerical schemes of adjoint equations are obtained through numerical methods. Firstly, the continuous adjoint equations are linear equations and evolve from the end simulation time. The convection velocity direction of the continuous adjoint saturation equation is opposite to the convection direction of the saturation equation. Secondly, the total simulation time has significant impact on the adjoint variables and the adjoint gradient. After water breakthrough in production well, the adjoint variables exhibit spatial variety that gradually changes from production well to injection well. With this observation, we find that this variety is related to the fractional flow function and its derivative value. The sharp change of fractional flow function and its derivative at the end of the simulation time can lead to large fluctuation of the adjoint gradient along the time step. Thirdly, the influence of time interval on optimization results is studied. Increasing the number of time steps will increase the optimal value, but the value of the difference between optimal and initial value will not increase significantly. When the variable number of time steps is adopted, this difference decreases as the number of time steps increases, which indicates that the coarse time step optimization can provide a better initial control value for the fine time step optimization. An adaptive time step from coarse step to fine step is thus recommended for optimization.

A Generalized Cubic Exponential B-Spline Scheme with Shape Control

In this paper, a generalized cubic exponential B-spline scheme is presented, which can generate different kinds of curves, including the conics. Such a scheme is obtained by generalizing the cubic exponential B-spline scheme based on an iteration from the generation of exponential polynomials and a suitable function with two parameters μ and ν. By changing the values of μ and ν, the sensitivity of the shape of the subdivision curve to the initial control value v0 can be changed and different kinds of curves can then be obtained by adjusting the value of v0. For this new scheme, we show that, with any admissible choice of μ and ν, it owns the same smoothness order and support as the cubic exponential B-spline scheme. Besides, based on a different iteration and another suitable function, we construct a similar nonstationary scheme to generate more curves with different shapes and show the role of iterations and suitably chosen functions in the construction and analysis of such schemes. Several examples are given to illustrate the performance of our new schemes.

Ultrasound Stimulation of Insulin Release from Pancreatic Beta Cells as a Potential Novel Treatment for Type 2 Diabetes

Type 2 diabetes mellitus is a complex metabolic disease that has reached epidemic proportions in the United States and around the world. This disease is characterized by loss of insulin secretion and, eventually, destruction of insulin-producing pancreatic beta cells. Controlling type 2 diabetes is often difficult as pharmacological management routinely requires complex therapy with multiple medications, and loses its effectiveness over time. The objective of this study was to explore the effectiveness of a novel, non-pharmacological approach that uses the application of ultrasound energy to augment insulin release from rat INS 832/13 beta cells. The cells were exposed to unfocused ultrasound for 5 min at a peak intensity of 1 W/cm2 and frequencies of 400 kHz, 600 kHz, 800 kHz and 1 MHz. Insulin release was measured with enzyme-linked immunosorbent assay and cell viability was assessed via the trypan blue dye exclusion test. A marked release (approximately 150 ng/106 cells, p < 0.05) of insulin was observed when beta cells were exposed to ultrasound at 400 and 600 kHz as compared with their initial control values; however, this release was accompanied by a substantial loss in cell viability. Ultrasound application at frequencies of 800 kHz resulted in 24 ng/106 cells released insulin (p < 0.05) as compared with its unstimulated base level, while retaining cell viability. Insulin release from beta cells caused by application of 800-kHz ultrasound was comparable to that reported by the secretagogue glucose, thus operating within physiological secretory capacity of these cells. Ultrasound has potential as a novel and alternative method to current approaches aimed at correcting secretory deficiencies in patients with type 2 diabetes.

Nesting behavior is associated with increased urinary volume in the urinary bladder during the reproductive period in small-egged Kajika, Cottus pollux SE

We found that male small-egged Kajika, Cottus pollux SE sensu Yokoyama and Goto (2005), retained a large volume of urine (approximately, 1 % body weight) in their urinary bladder while nesting under spawning sub- strate. This increase in urine volume occurred three days after the males were transferred to the nesting tank. Serum 11-ketotestosterone (11-KT) concentrations of males also increased approximately twofold after the males were transferred to the nesting tank. While this increase in the urinary volume was observed only during the reproductive period (late December), the increase in serum 11-KT concentration from the basal levels associated with nesting occurred from the spermatogenic period (from October to mid-December) to the reproductive period (late Decem- ber). These findings suggest that the urine of nesting males plays a role in reproduction, whereas the increase in serum 11-KT levels may be associated with social status/domi- nance. The increased urine due to nesting contained an approximately sixfold level of 11-KT compared to the initial control values, suggesting that the urine of nesting male Kajika may have functioned as social signals to females and/or to other males.

Effects of maxillary expansion rate on the nasopharyngeal airway in the mixed dentition

Objective: To evaluate the effects of maxillary expansion rate on nasopharyngeal airway in the mixed dentition period. Materials and Methods: Three groups of the patients were individually treated with semi-rapid maxillary expansion (SRME), rapid maxillary expansion (RME), and removable appliance without expansion (control group). Mean age values were 8.63 ΁ 1.09 years for the SRME group (18 patients: 11 girls and 7 boys), 8.78 ΁ 1.21 years for the RME group (17 patients: 11 girls and 6 boys), and 10.5 ΁ 1.01 years for the control group (16 patients: 6 girls and 10 boys). Screw activation was conducted two-quarter turns per day during the treatment in RME group. Same activation order was used for SRME group for the first week, followed by one-quarter turn every 2 days. Intragroup comparisons were evaluated by paired samples t -test and intergroup changes were analyzed with an analysis of variance (ANOVA). Post-hoc multiple comparisons were done by Tukey's Honestly Significance Difference (HSD) test. Results: For both SRME and RME groups, changes in aerial and total airway measurements were statistically significant when compared to the control group (SRME vs. control: P = 0.049 in aerial, P = 0.038 total airway; RME vs. control: P = 0.048 in aerial, P = 0.011 total airway). When both treatment groups were compared, no statistically significant differences were found in any of the measurements. Conclusions: SRME and RME had significant effects on craniofacial airway dimensions when compared to initial values or untreated control values. Changes in airway dimension were similar in the SRME and RME groups.

Comparison of the expression in Saccharomyces cerevisiae of endoglucanase II from Trichoderma reesei and endoglucanase I from Aspergillus aculeatus

Two distinct expression cassettes were synthesized by overlapping PCR for expressing the endoglucanase I gene (egl1) from Aspergillus aculeatus and the endoglucanase II gene (egl2) from Trichoderma reesei in a Saccharomyces cerevisiae host. One contained the anchored sequence from the S. cerevisiae cwp2 gene, while the other did not. The low and high copy number plasmids YCplac33 and YEplac195 were used. The enzymatic activities and viscosity changes in the YP-CMC medium varied between the eight recombinant yeast strains produced, and the greatest values were obtained with the YE-TrEII’ strain, which had an activity of 347.7 U/g dry cell weight (DCW) and viscosity at 12 h of 4.7% of the initial control value, respectively; YE-TrEII’ was YEplac195-based and contained T. reesei egl2 and no Cwp2 sequence. Strains YC-AaEI and YC-TrEII showed the lowest enzyme activitiy (80.5 and 30.4 U/g DCW, respectively) and viscosity changes at 12 h (20.5 and 26.2% of the initial control viscosity, respectively), which were YCplac33-based and contained the Cwp2 sequence. The results showed that gene copy number was the most significant factor to influence the expression of endoglucanases in S. cerevisiae, and the existence of Cwp2 sequence led to decreased enzymatic level and viscosity-reducing performance, while it was shown not to realize efficient surface display of these two endoglucanases.

Endogenous SNAP-25 Regulates Native Voltage-gated Calcium Channels in Glutamatergic Neurons

In addition to its primary role as a fundamental component of the SNARE complex, SNAP-25 also modulates voltage-gated calcium channels (VGCCs) in various overexpression systems. Although these studies suggest a potential negative regulatory role of SNAP-25 on VGCC activity, the effects of endogenous SNAP-25 on native VGCC function in neurons are unclear. In the present study, we investigated the VGCC properties of cultured glutamatergic and GABAergic rat hippocampal neurons. Glutamatergic currents were dominated by P/Q-type channels, whereas GABAergic cells had a dominant L-type component. Also, glutamatergic VGCC current densities were significantly lower with enhanced inactivation rates and shifts in the voltage dependence of activation and inactivation curves compared with GABAergic cells. Silencing endogenous SNAP-25 in glutamatergic neurons did not alter P/Q-type channel expression or localization but led to increased VGCC current density without changes in the VGCC subtype proportions. Isolation of the P/Q-type component indicated that increased current in the absence of SNAP-25 was correlated with a large depolarizing shift in the voltage dependence of inactivation. Overexpressing SNAP-25 in GABAergic neurons reduced current density without affecting the VGCC subtype proportion. Accordingly, VGCC current densities in glutamatergic neurons from Snap-25(+/-) mice were significantly elevated compared with wild type glutamatergic neurons. Overall, this study demonstrates that endogenous SNAP-25 negatively regulates native VGCCs in glutamatergic neurons which could have important implications for neurological diseases associated with altered SNAP-25 expression.

Changes in fetal myocardial glycogen during hypoxia induced by maternal acute hemorrhagic shock.

Fetal and maternal metabolic and hemodynamic changes, with special reference to fetal myocardial glycogen, were investigated during hypoxia induced by maternal acute hemorrhage. Myocardial glycogen gradually decreased during the hypotensive period to nearly half the initial control value. Linear relationships were observed between miocardial glycogen and fetal pH and fetal heart rate. The role of myocardial glycogen in cardiac function and its metabolic changes during hyposica were evaluated.

Femoral Head Deformation and Repair Following Induction of Ischemic Necrosis

Ischemic necrosis of the femoral head can be induced surgically in the piglet. We used this model to assess femoral head deformation and repair in vivo by sequential magnetic resonance imaging and by correlating end-stage findings with histologic assessments. Ischemic necrosis of the femoral head was induced in ten three-week-old piglets by tying a silk ligature around the base of the femoral neck (intracapsular) and cutting the ligamentum teres. We used magnetic resonance imaging with the piglets under general anesthesia to study the hips at forty-eight hours and at one, two, four, and eight weeks. Measurements on magnetic resonance images in the midcoronal plane of the involved and control sides at each time documented the femoral head height, femoral head width, superior surface cartilage height, and femoral neck-shaft angle. Histologic assessments were done at the time of killing. Complete ischemia of the femoral head was identified in all involved femora by magnetic resonance imaging at forty-eight hours. Revascularization began at the periphery of the femoral head as early as one week and was underway in all by two weeks. At eight weeks, magnetic resonance imaging and histologic analysis showed deformation of the femoral head and variable tissue deposition. Tissue responses included (1) vascularized fibroblastic ingrowth with tissue resorption and cartilage, intramembranous bone, and mixed fibro-osseous or fibro-cartilaginous tissue synthesis and (2) resumption of endochondral bone growth. At eight weeks, the mean femoral head measurements (and standard error of the mean) for the control compared with the ligated femora were 10.4 +/- 0.4 and 4.8 +/- 0.4 mm, respectively, for height; 26.7 +/- 0.8 and 31.2 +/- 0.8 mm for diameter; 1.1 +/- 0.1 and 2.3 +/- 0.1 mm for cartilage thickness; and 151 degrees +/- 2 degrees and 135 degrees +/- 2 degrees for the femoral neck-shaft angle. Repeated-measures mixed-model analysis of variance revealed highly significant effects of ligation in each parameter (p < 0.0001). Magnetic resonance imaging allows for the assessment of individual hips at sequential time periods to follow deformation and repair. There was a variable tissue response, and histologic assessment at the time of killing was shown to correlate with the evolving and varying magnetic resonance imaging signal intensities. Femoral head height on the ischemic side from one week onward was always less than the initial control value and continually decreased with time, indicating collapse as well as slowed growth. Increased femoral head width occurred relatively late (four to eight weeks), indicating cartilage model overgrowth concentrated at the periphery.

Identifying coronary artery flow reduction and ischemia using quasistationary QT/RR-interval hysteresis measurements

Because myocardial ischemia induces QT/RR hysteresis, a correlation was hypothesized to exist between the extent of myocardial flow reduction and the magnitude of QT/RR hysteresis. Graded reductions in regional myocardial perfusion in the distribution of the left anterior descending coronary artery in open-chest pigs were used to model 1-vessel coronary artery disease. At each reduced level of left anterior descending coronary artery flow, the heart was electrically paced at progressively higher and lower rates between an initial control and maximum heart rate values. Digitized surface and intramyocardial electrograms and aortic pressure were used to measure QT/RR hysteresis, QT-interval adaptation, ST- and TQ-segment depression, and cardiac contractility. Intraexperimental blood samples were analyzed to assess inflammatory response (interleukin 6), oxidative stress (protein carbonyls), and myocyte injury (creatine kinase). Higher values of QT/RR hysteresis correlated with the severity of ischemia as assessed by TQ-segment depression in intramyocardial electrograms ( P = .002). Lower flow rates were strongly associated with higher values of QT/RR hysteresis and slower QT-interval adaptation ( P ≤ .004), and were less correlated with the magnitude of ST- and TQ-segment depression ( P ≥ .02). Significant increases in systemic measures of inflammation, oxidative stress, and cardiac myocyte injury and major decrease in cardiac contractility preceded the most severe stages of flow reduction (30% and 20% of normal flow). We determined QT/RR hysteresis index thresholds corresponding to these mechanical and immunochemical responses. QT/RR hysteresis is a strong indicator of reduced myocardial perfusion and may provide information for noninvasive assessment of mechanical and immunochemical changes associated with early stages of coronary artery disease.

Ouabain augments and maintains the catecholamine release responses evoked by repetitive pulses of potassium, caffeine or histamine in perifused bovine chromaffin cells

Cardiac glycosides such as ouabain augment the release of neurotransmitters and hormones from various organs, tissues and cell systems. Here we have investigated novel aspects of the ouabain effects on fast-perifused bovine adrenal chromaffin cells subjected to repetitive stimulation during long-time periods with secretagogues that enhance Ca 2+ entry (i.e. 100 mM K +solution) or causing the release into the cytosol of the Ca 2+ stored in the endoplasmic reticulum (i.e. 20 mM caffeine or 100 μM histamine). After 1 h of intermittent stimulation, the amperometrically measured catecholamine release responses decayed to 50% with K + pulses, and to 10–15% with caffeine or histamine pulses. Ouabain (10 μM) augmented 2-fold the K + secretory responses and kept them high, along an hour. When given after the responses had decayed upon repetitive caffeine or histamine pulsing, ouabain gradually restored such responses to their initial control values. On the basis of these results, we raise the hypothesis that ouabain may facilitate the handling by the cell of the endoplasmic reticulum Ca 2+ fluxes that are known to be involved in secretory vesicle transport and the regulation of exocytosis. This may have physiological and pathological interest in the light of an endogenous ouabain steroid found in the adrenal cortex.

Effect of Ramadan fasting on fuel oxidation during exercise in trained male rugby players

The aim of this study was to assess the effect of Ramadan fasting on substrate oxidation in trained athletes during moderate-intensity exercise. Nine trained men (age: 19+/-2 yr, Height: 1.78+/-0.74 m) were tested on three occasions: during a control period immediately before Ramadan (C), at the end of the first week (Beg-R), and during the fourth week of Ramadan (End-R). On each occasion, they performed submaximal cycle ergometer exercise, with work-rates that were increased progressively (loadings corresponding to 20, 30, 40, 50, 60% of Wmax). Steady-state substrate oxidation was evaluated by indirect calorimetry. Participants showed significant decreases in body mass and body fat at the end of Ramadan, relative to initial control values (P<0.001). The daily food intake was also reduced during Ramadan (P<0.01). Haemoglobin concentrations and hematocrit were significantly higher at the end-Ramadan, both at rest (P<0.001 and P<0.0001 respectively) and after exercise, (P<0.05 and P<0.01 respectively) compared to control measurements made before Ramadan. At the end of Ramadan, our subjects had increased their fat utilization during exercise. The cross-over was observed at a higher intensity at the End-R (35% vs. 30% of Wmax, P<0.001). For the same power output, the Lipox max was also higher at the End-R, compared to control value (265+/-38 vs. 199.1+/-20 mg/min, P<0.001). Ramadan fasting increases the lipid oxidation of trained athletes during submaximal exercise. The increased fat utilisation may be related to decreases in body mass and body fat content.

Redistribution of cardiac output during hemorrhagic shock in sheep

Our goal was to evaluate the robustness of one of the assumptions used by esophageal Doppler monitors to compute systemic stroke volume and cardiac output; i.e., a constant flow proportion between supra-aortic vessels and descending aorta. For this purpose, we measured ascending and descending aortic blood flows during acute hemorrhage in anesthetized ewes. Prospective, experimental study. Animal research facility. Adult ewes. Anesthetized animals were implemented with an aortic pressure transducer and two ultrasound transit time flowmeters placed around ascending and descending aorta, respectively. After baseline measurements, three incremental blood withdrawals were followed by progressive blood restitution in three similar steps. Ascending and descending aortic blood flows were reduced in a proportional manner after hemorrhage (-48% and -46%, respectively; p < .05 vs. baseline). Following blood restitution, flows were not fully restored, but ascending aortic flow was reduced by 27% with respect to initial control values while descending aortic flow was only 15% below. The agreement between ascending aortic flow and cardiac output calculated as descending aortic flow divided by 0.7 was characterized by a bias of 0.07 L/min and limits of agreement of +1.24 L/min and -1.10 L/min. Minor blood flow redistribution between supra-aortic and descending aortic territories was seen only following blood restitution but not during hemorrhage in these anesthetized ewes. This observation supports the robustness of the assumption of constant flow proportion used by the esophageal Doppler monitor to calculate systemic stroke volume from descending aortic flow measurements.