Substantial cardiac parasympathetic activity exists during heavy dynamic exercise in dogs

1997 ◽  
Vol 273 (5) ◽  
pp. H2135-H2140 ◽  
Author(s):  
Donal S. O’Leary ◽  
Noreen F. Rossi ◽  
Paul C. Churchill
Keyword(s):  
Steady State ◽  
Sympathetic Nerves ◽  
Cholinergic Receptor ◽  
Dynamic Exercise ◽  
Aortic Blood Flow ◽  
Receptor Blockade ◽  
Parasympathetic Nerves ◽  
Wide Range ◽  
Before And After ◽  
Β Receptor

We investigated the extent of functional parasympathetic and sympathetic activity to the heart at rest and during mild to heavy dynamic exercise in conscious dogs. The animals were chronically instrumented to monitor mean arterial pressure (MAP), heart rate (HR), and terminal aortic blood flow (TAQ) and trained to run on a motor-driven treadmill. MAP, HR, and TAQ were monitored at rest and during steady-state dynamic exercise ranging from mild [3.2 kilometers per hour (kph), 0% grade] to heavy exercise (8 kph, 15% grade). Experiments were performed before and after blocking the effects of either the parasympathetic nerves (atropine 0.2 mg/kg iv) or sympathetic nerves (atenolol 2.0 mg/kg iv) to the heart. In addition, blood samples were taken at rest and at steady state during exercise, and plasma levels of vasopressin and renin activity were assessed. At rest and during all levels of exercise, muscarinic cholinergic receptor blockade caused a marked increase in HR over control (saline treated) levels with little effect on MAP or TAQ. β-Adrenergic receptor blockade had no significant effect on HR at rest and during mild exercise. At moderate to heavy workloads, β-receptor blockade significantly reduced MAP, HR, and TAQ and increased plasma vasopressin levels. We conclude that, even during heavy dynamic exercise, significant functional parasympathetic tone to the heart exists. Thus, over a wide range of exercise workloads, HR is under the tonic control of both sympathetic and parasympathetic nerves.

Effects of combined histamine H1 and H2 receptor blockade on hemodynamic responses to dynamic exercise in males with high-normal blood pressure

2020 ◽  
Vol 45 (7) ◽  
pp. 769-776
Author(s):  
Ashley Naylor ◽  
Brian Shariffi ◽  
Trevor L. Gillum ◽  
Boyer William ◽  
Sean Sullivan ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Dynamic Exercise ◽  
Histamine Receptors ◽  
Normal Group ◽  
Receptor Blockade ◽  
Peripheral Vasoconstriction ◽  
Before And After ◽  
Group A ◽  
Postexercise Hypotension ◽  
Response To Exercise

While postexercise hypotension is associated with histamine H1 and H2 receptor-mediated postexercise vasodilation, effects of histaminergic vasodilation on blood pressure (BP) in response to dynamic exercise are not known. Thus, in 20 recreationally active male participants (10 normotensive and 10 with high-normal BP) we examined the effects of histamine H1 and H2 receptor blockade on cardiac output (CO), mean atrial pressure (MAP), aortic stiffness (AoStiff), and total vascular conductance (TVC) at rest and during progressive cycling exercise. Compared with the normotensive group, MAP, CO, and AoStiff were higher in the high-normal group before and after the blockade at rest, while TVC was similar. At the 40% workload, the blockade significantly increased MAP in both groups, while no difference was found in the TVC. CO was higher in the high-normal group than the normotensive group in both conditions. At the 60% workload, the blockade substantially increased MAP and decreased TVC in the normotensive group, while there were no changes in the high-normal group. A similar CO response pattern was observed at the 60% workload. These findings suggest that the mechanism eliciting an exaggerated BP response to exercise in the high-normal group may be partially due to the inability of histamine receptors. Novelty Males with high-normal BP had an exaggerated BP response to exercise. The overactive BP response is known due to an increase in peripheral vasoconstriction. Increase in peripheral vasoconstriction is partially due to inability of histamine receptors.

Haemodynamic Responses to Exercise and Acute β-Receptor Blockade in Renin Sub-Types of Essential Hypertension

1976 ◽  
Vol 51 (s3) ◽  
pp. 493s-496s ◽  
Author(s):  
F. Burkart ◽  
F. R. Bühler ◽  
M. Pfisterer ◽  
B. E. Lütold ◽  
M. Küng
Keyword(s):  
Essential Hypertension ◽  
Plasma Renin ◽  
Receptor Blockade ◽  
Control Mechanisms ◽  
Exercise Tachycardia ◽  
Adrenergic Control ◽  
Before And After ◽  
Pre Treatment ◽  
Β Receptor

1. Haemodynamic and renin responses to dynamic exercise before and after intravenous β-adrenoreceptor blockade with propranolol were compared in twenty-one patients with essential hypertension and either high (n = 7), normal (n = 7) or low plasma renin activity (n = 7). 2. Renin and heart-rate responses to exercise and β-receptor blockade diminished from high-renin to normal and to low-renin patients, effects which were blunted with increasing age. 3. Among the renin groups cardiac output, stroke volume, diastolic pulmonary artery pressure, systemic pressure and peripheral vascular resistance as well as their changes produced by exercise and acute β-receptor blockade were not significantly different. 4. Long-term anti-hypertensive propranolol effects correlated with the pre-treatment renin status, renin stimulation and its suppression by acute β-receptor blockade as well as with the exercise tachycardia and the patient's age. 5. The results suggest different adrenergic control mechanisms in renin sub-types of essential hypertension, age being a modulating factor.

Rectal and intravenous propranolol infusion to steady state: Kinetics and β-receptor blockade

1984 ◽  
Vol 35 (2) ◽  
pp. 148-155 ◽  
Author(s):  
Leo G J de Leede ◽  
Carl C Hug ◽  
Simon de Lange ◽  
Albertus G de Boer ◽  
Douwe D Breimer
Keyword(s):  
Steady State ◽  
Receptor Blockade ◽  
Steady State Kinetics ◽  
Β Receptor

Rabbit carotid baroreflexes after carotid sympathectomy, vagotomy, and beta blockade

1981 ◽  
Vol 241 (4) ◽  
pp. H600-H605 ◽  
Author(s):  
H. O. Stinnett ◽  
F. J. Sepe ◽  
M. R. Mangusson
Keyword(s):  
Sympathetic Denervation ◽  
Beta Blockade ◽  
Receptor Blockade ◽  
Beta Receptor ◽  
Comparison Of Results ◽  
Wide Range ◽  
Before And After ◽  
Cervical Vagotomy ◽  
Beta Receptor Blockade ◽  
Cervical Ganglia

Factors that modify carotid vascular baroreflexes were studied in anesthetized rabbits after section of the cervical aortic nerves. We recorded steady-state reflex responses of heart rate (HR) and mean arterial pressure (MAP) to changes in isolated nonpulsatile carotid intrasinus pressures (ISP) over a wide range. These measurements and the procedures were repeated 1) after sympathetic denervation of the carotid sinuses by section of the cervical sympathetic nerve below the superior cervical ganglia; 2) after cervical vagotomy; and 3) after beta-receptor blockade by propranolol administration. The linearity of the MAP-ISP relation curve slope was determined between ISP levels of 63 and 100 mmHg. Comparison of results before and after sympathetic denervation of the sinuses indicated that the denervation significantly lowered the position of the MAP-ISP relation curve over a mid-ISP range. Subsequent vagotomy significantly elevated both HR-ISP relation curve and MAP-ISP relation curve. AFter beta-receptor blockade HR remained constant, whereas the slope of the MAP-ISP relation curve decreased to -1.34 from the slope of -2.26 before blockade. Comparison of results before and after beta blockade in the vagotomized animals suggested a substantial cardiac influence on carotid reflex control of MAP.

Spectroscopic Studies of Asparaginyl-tRNA Synthetase from Entamoeba histolytica

2019 ◽  
Vol 26 (6) ◽  
pp. 435-448
Author(s):  
Priyanka Biswas ◽  
Dillip K. Sahu ◽  
Kalyanasis Sahu ◽  
Rajat Banerjee
Keyword(s):  
Circular Dichroism ◽  
Steady State ◽  
Entamoeba Histolytica ◽  
Protein Concentration ◽  
Trna Synthetase ◽  
Solvent Exposure ◽  
Steady State Fluorescence ◽  
State Process ◽  
Wide Range ◽  
Circular Dichroïsm

Background: Aminoacyl-tRNA synthetases play an important role in catalyzing the first step in protein synthesis by attaching the appropriate amino acid to its cognate tRNA which then transported to the growing polypeptide chain. Asparaginyl-tRNA Synthetase (AsnRS) from Brugia malayi, Leishmania major, Thermus thermophilus, Trypanosoma brucei have been shown to play an important role in survival and pathogenesis. Entamoeba histolytica (Ehis) is an anaerobic eukaryotic pathogen that infects the large intestines of humans. It is a major cause of dysentery and has the potential to cause life-threatening abscesses in the liver and other organs making it the second leading cause of parasitic death after malaria. Ehis-AsnRS has not been studied in detail, except the crystal structure determined at 3 Å resolution showing that it is primarily α-helical and dimeric. It is a homodimer, with each 52 kDa monomer consisting of 451 amino acids. It has a relatively short N-terminal as compared to its human and yeast counterparts. Objective: Our study focusses to understand certain structural characteristics of Ehis-AsnRS using biophysical tools to decipher the thermodynamics of unfolding and its binding properties. Methods: Ehis-AsnRS was cloned and expressed in E. coli BL21DE3 cells. Protein purification was performed using Ni-NTA affinity chromatography, following which the protein was used for biophysical studies. Various techniques such as steady-state fluorescence, quenching, circular dichroism, differential scanning fluorimetry, isothermal calorimetry and fluorescence lifetime studies were employed for the conformational characterization of Ehis-AsnRS. Protein concentration for far-UV and near-UV circular dichroism experiments was 8 µM and 20 µM respectively, while 4 µM protein was used for the rest of the experiments. Results: The present study revealed that Ehis-AsnRS undergoes unfolding when subjected to increasing concentration of GdnHCl and the process is reversible. With increasing temperature, it retains its structural compactness up to 45ºC before it unfolds. Steady-state fluorescence, circular dichroism and hydrophobic dye binding experiments cumulatively suggest that Ehis-AsnRS undergoes a two-state transition during unfolding. Shifting of the transition mid-point with increasing protein concentration further illustrate that dissociation and unfolding processes are coupled indicating the absence of any detectable folded monomer. Conclusion: This article indicates that GdnHCl induced denaturation of Ehis-AsnRS is a two – state process and does not involve any intermediate; unfolding occurs directly from native dimer to unfolded monomer. The solvent exposure of the tryptophan residues is biphasic, indicating selective quenching. Ehis-AsnRS also exhibits a structural as well as functional stability over a wide range of pH.

Perioperative Skin Conditioning for Patients With Skin of Color

2021 ◽  
pp. 074880682198989
Author(s):  
Alix Ferdinand ◽  
Suzan Obagi
Keyword(s):  
Treatment Regimen ◽  
Skin Care ◽  
Practical Approach ◽  
Postoperative Phase ◽  
Upward Trend ◽  
Wide Range ◽  
Before And After

The interest in cosmetic procedures for patients with skin of color is on an upward trend. Globally, dyschromia and hyperpigmentation remain the most common disorders for which patients seek treatment. The goals of a perioperative skin conditioning program include allowing a broad range of patients to be treated regardless of skin phototypes, maximizing results, and reducing risk of complications such as post-inflammatory hyperpigmentation and managing post-inflammatory hyperpigmentation if it occurs. The purpose of this article is to highlight common pigmentation concerns among patients with skin of color, the topical agents used to combat these concerns, and a practical approach to creating an effective yet straightforward topical skin care regimen that can be used across a wide range of patient skin phototypes. Before and after photos of patients with a variety of pigmentation concerns are presented along with a description of the treatment regimen used to improve their conditions and to get their skin to a safer state prior to performing any office-based procedures. By understanding the main concerns of patients with skin of color, one can use a simple and effective skincare regimen to allow these patients to be more safely treated. An effective skincare regimen both prepares the skin prior to procedures and postoperatively to help minimize dyschromias in the postoperative phase.

scholarly journals Identification of DC Thermal Steady-State Differential Inductance of Ferrite Power Inductors

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3854
Author(s):  
Salvatore Musumeci ◽  
Luigi Solimene ◽  
Carlo Stefano Ragusa
Keyword(s):  
Steady State ◽  
Input Voltage ◽  
Switching Frequency ◽  
Ohmic Losses ◽  
Steady State Temperature ◽  
Wide Range ◽  
Average Current ◽  
Power Inductors ◽  
Saturable Inductor ◽  
Thermal Steady State

In this paper, we propose a method for the identification of the differential inductance of saturable ferrite inductors adopted in DC–DC converters, considering the influence of the operating temperature. The inductor temperature rise is caused mainly by its losses, neglecting the heating contribution by the other components forming the converter layout. When the ohmic losses caused by the average current represent the principal portion of the inductor power losses, the steady-state temperature of the component can be related to the average current value. Under this assumption, usual for saturable inductors in DC–DC converters, the presented experimental setup and characterization method allow identifying a DC thermal steady-state differential inductance profile of a ferrite inductor. The curve is obtained from experimental measurements of the inductor voltage and current waveforms, at different average current values, that lead the component to operate from the linear region of the magnetization curve up to the saturation. The obtained inductance profile can be adopted to simulate the current waveform of a saturable inductor in a DC–DC converter, providing accurate results under a wide range of switching frequency, input voltage, duty cycle, and output current values.

scholarly journals Changes in Cellular Regulatory Factors before and after Decompression of Odontogenic Keratocysts

2020 ◽  
Vol 10 (1) ◽  
pp. 30
Author(s):  
Slmaro Park ◽  
Han-Sung Jung ◽  
Young-Soo Jung ◽  
Woong Nam ◽  
Jung Yul Cha ◽  
...  
Keyword(s):  
Recurrence Rate ◽  
Biological Behavior ◽  
Nuclear Antigen ◽  
Epithelial Cyst ◽  
Ki 67 ◽  
Proliferation Markers ◽  
Odontogenic Keratocysts ◽  
Wide Range ◽  
Before And After ◽  
Cyst Lining

Decompression followed by enucleation, which is one of the treatments used for odontogenic keratocysts (OKCs), is frequently used in OKC lesions of large sizes. This method offers the advantage of minimizing the possibility of sensory impairment without creating a wide-range bone defect; moreover, the recurrence rate can be significantly lower than following simple enucleation. This study aimed to assess the changes in histology and expression of proliferation markers in OKCs before and after decompression treatment. A total of 38 OKC tissue samples from 19 patients who had undergone decompression therapy were examined morphologically and immunohistochemically to observe changes in proliferative activity before and after decompression. The markers used for immunohistochemistry (IHC) staining were Bcl-2, epidermal growth factor receptor (EGFR), Ki-67, P53, PCNA, and SMO. The immunohistochemistry positivity of the 6 markers was scored by using software ImageJ, version 1.49, by quantifying the intensity and internal density of IHC-stained epithelium. The values of Bcl-2, Ki-67, P53, proliferating cell nuclear antigen (PCNA), and SMO in OKCs before and after decompression showed no significant change. No correlation between clinical shrinkage and morphologic changes or expression of proliferation and growth markers could be found. There was no statistical evidence that decompression treatment reduces potentially aggressive behavior of OKC within the epithelial cyst lining itself. This might indicate that decompression does not change the biological behavior of the epithelial cyst lining or the recurrence rate.

SET-VALUED PERFORMANCE APPROXIMATIONS FOR THE QUEUE GIVEN PARTIAL INFORMATION

2020 ◽  
pp. 1-23
Author(s):  
Yan Chen ◽  
Ward Whitt
Keyword(s):  
Steady State ◽  
Decay Rate ◽  
Waiting Time ◽  
Partial Information ◽  
Upper And Lower Bounds ◽  
Interarrival Time ◽  
Limited Information ◽  
Wide Range ◽  
The Mean ◽  
Third Moment

In order to understand queueing performance given only partial information about the model, we propose determining intervals of likely values of performance measures given that limited information. We illustrate this approach for the mean steady-state waiting time in the $GI/GI/K$ queue. We start by specifying the first two moments of the interarrival-time and service-time distributions, and then consider additional information about these underlying distributions, in particular, a third moment and a Laplace transform value. As a theoretical basis, we apply extremal models yielding tight upper and lower bounds on the asymptotic decay rate of the steady-state waiting-time tail probability. We illustrate by constructing the theoretically justified intervals of values for the decay rate and the associated heuristically determined interval of values for the mean waiting times. Without extra information, the extremal models involve two-point distributions, which yield a wide range for the mean. Adding constraints on the third moment and a transform value produces three-point extremal distributions, which significantly reduce the range, producing practical levels of accuracy.

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