Defense mechanisms to increasing back pressure for hepatic oxygen transport and venous return in porcine fecal peritonitis

2020 ◽  
Vol 319 (3) ◽  
pp. G289-G302
Author(s):  
Shengchen Liu ◽  
Pedro Paulo Zanella do Amaral Campos ◽  
Daniela Casoni ◽  
David Berger ◽  
Andreas Kohler ◽  
...  
Keyword(s):  
Oxygen Transport ◽  
Defense Mechanisms ◽  
Venous Return ◽  
Back Pressure ◽  
Fecal Peritonitis

Sepsis impairs intrinsic mechanisms to attenuate effects of increasing back pressure on hepatic oxygen transport.

Effects of decreasing lung compliance with oleic acid on the cardiovascular response to PEEP

1977 ◽  
Vol 233 (6) ◽  
pp. H635-H641 ◽  
Author(s):  
S. M. Scharf ◽  
R. H. Ingram
Keyword(s):  
Oleic Acid ◽  
Venous Return ◽  
Cardiovascular Response ◽  
Lung Compliance ◽  
Back Pressure ◽  
Right Atrial ◽  
Positive End Expiratory Pressure ◽  
Chest Wall Compliance ◽  
Before And After ◽  
Wall Compliance

In 12 anesthetized mongrel dogs on a constant volume ventilator, the response of the cardiovascular system to increasing positive end-expiratory pressure (PEEP) was examined before and after inducing acute lung injury with oleic acid. As PEEP was raised to approximately 16 mmHg, lung volume increased by approximately 900 ml before oleic acid and only 350 ml after. Pleural pressure increased by the same amount, indicating that both lung and chest wall compliance decreased with oleic acid. Right atrial pressure, the back pressure to venous return, also increased by the same amount. Although cardiac output at PEEP = 0 was lower after oleic acid, the relative decrements produced by increasing PEEP were the same as before oleic acid.

Research Including Persons with Disabilities: Practical Issues and Contributions to Knowledge of Exercise Physiology

1993 ◽  
Vol 10 (4) ◽  
pp. 336-345
Author(s):  
Roy J. Shephard
Keyword(s):  
Young Children ◽  
Oxygen Transport ◽  
Daily Living ◽  
Aerobic Training ◽  
Venous Return ◽  
Exercise Physiology ◽  
Sympathetic Innervation ◽  
Vigorous Exercise ◽  
Persons With Disabilities ◽  
Ethical Concerns

Attention is drawn to specific practical and ethical concerns that may arise when researchers study responses to vigorous exercise in populations with disabilities. It is argued that the study of such individuals can provide important information regarding responses to exercise by nondisabled people. This thesis is illustrated by selected examples relating to (a) central versus peripheral limitation of oxygen transport, (b) the contribution of muscle pumping to venous return during vigorous exercise, (c) the contribution of sympathetic innervation to aerobic training responses, (d) the ceiling of muscle fiber hypertrophy, (e) the functional demands of daily living, and (f) the responsiveness of young children to aerobic training. It is concluded that exercise physiologists have already learned much about normal reactions to exercise by studies involving those disabilities, but there remains scope for many further investigations exploiting the special characteristics of such populations.

scholarly journals Indicators of oxygen transport in acute and early periods of traumatic disease with multistage surgical correction at polytrauma

2020 ◽  
Keyword(s):  
Intensive Care ◽  
Oxygen Transport ◽  
Defense Mechanisms ◽  
Perioperative Period ◽  
Multiple Organ ◽  
Pathological Process ◽  
Surgical Correction ◽  
Compensatory Mechanisms ◽  
Oxygen Homeostasis ◽  
Multi Stage

Disorders of the oxygen transport play an important role in the development of multiple organ disfunction syndrome and are a marker of tissue hypoxia and ischemia. Disorders of the oxygen transport could be use for predicting patient survival and as criteria for the severity of the pathological process. The aim of this study was to explore the indicators of systemic oxygen transport in the perioperative period in patients with traumatic deases in multi-stage surgical correction at polytrauma in terms of standard and advanced intensive care. Materials and methods. A prospective study of 88 patients with traumatic deases was conducted. The dynamics of indices of oxygen delivery (iDО2) and oxygen consumption (iVO2), oxygen extraction coefficient (KEO2) at different variants of intensive care was studied. Results. The patients in both groups was noted iDO2 decline, which was due to massive blood loss and decreased cardiac output on admission to the operation room. Despite the fact that during the acute period was held stop bleeding, correction of hypovolemia and posthemorrhagic anemia, the average level of iDО2 was quite low. iDO2 was multidirectional nature of the changes in the studied groups at the second and third stages of the study. In turn, the average values KEO2 characterized the degree of tension compensatory mechanisms and metabolic changes caused by hypoxia and hypoperfusion. Normalization of oxygen homeostasis parameters was achieved in the fourth stage of the study. Conclusions. The maximal intensity of development of compensatory mechanisms and changes of oxygen transport occurs within the first 5 days after the injury. The optimized intensive care which has been used in the treatment patients of Group II, has positive effect on the ability to potentiate adaptive defense mechanisms and reduce oxygen debt.

A critical analysis of the view that right atrial pressure determines venous return

2003 ◽  
Vol 94 (3) ◽  
pp. 849-859 ◽  
Author(s):  
George L. Brengelmann
Keyword(s):  
Critical Analysis ◽  
Venous Return ◽  
Back Pressure ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Right Atrial Pressure ◽  
Input Output ◽  
The One ◽  
Mean Systemic Pressure

A. C. Guyton pioneered major advances in understanding cardiovascular equilibrium. He superimposed venous return curves on cardiac output curves to reveal their intersection at the one level of right atrial pressure (Pra) and flow simultaneously consistent with independent properties of the heart and vasculature. He showed how this point would change with altered properties of the heart (e.g., contractility, sensitivity to preload) and/or of the vasculature (e.g., resistance, total volume). In such graphical representations of negative feedback between two subdivisions of a system, one input/output relationship is necessarily plotted backward, i.e., with the input variable on the y-axis (here, the venous return curve). Unfortunately, this format encourages mistaken ideas about the role of Pra as a “back pressure,” such as the assertion that elevating Pra to the level of mean systemic pressure would stop venous return. These concepts are reexamined through review of the original experiments on venous return, presentation of a hypothetical alternative way for obtaining the same data, and analysis of a simple model.

Effects of endotoxin on isolated porcine liver: pressure-flow analysis

1995 ◽  
Vol 78 (3) ◽  
pp. 784-792 ◽  
Author(s):  
N. Brienza ◽  
T. Ayuse ◽  
J. P. Revelly ◽  
C. P. O'Donnell ◽  
J. L. Robotham
Keyword(s):  
Venous Return ◽  
Linear Regression Analysis ◽  
Flow Analysis ◽  
Back Pressure ◽  
Simultaneous Increase ◽  
Experimental Sepsis ◽  
Porcine Liver ◽  
Total Blood ◽  
Pressure Flow ◽  
Flow Pressure

The peripheral vascular response to sepsis is characterized by a vasodilatation of the systemic arterial vessels. Pulmonary hypertension with an increase in resistance and back pressure to flow defined by pressure-flow (P-Q) relationships has been reported in experimental sepsis. We hypothesized that endotoxin can induce differential alterations in resistance and back pressure to flow in the liver venous and arterial beds. Ninety minutes after endotoxin administration in intact anesthetized pigs (n = 8), the liver was vascularly isolated and perfused. Steady-state P-Q relationships in both the portal vein (PV) and hepatic artery (HA) were generated at multiple outflow pressures (Pout; 0, 5, 10, and 15 mmHg) and compared with those obtained in control livers (n = 6). Extrapolated zero-flow pressure intercepts (Pback) and slopes of the P-Q relationships were obtained by least squares linear regression analysis. Endotoxemia increased PV Pback (P < 0.05), and Pback always exceeded Pout (P < 0.05) when the latter was raised. In contrast, in controls, no difference was observed between Pback and Pout when the latter was raised. Endotoxemia also increased the PV slope compared with control. Raising Pout from 0 to 15 mmHg decreased PV slope in the endotoxin group to a greater degree than in controls (P < 0.05). In the HA, endotoxin caused a decrease in slope but did not alter Pback. The simultaneous increase in the PV Pback and slope that occurs with endotoxemia decreases splanchnic venous return, pooling blood in the splanchnic compartment for a given total blood volume.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Understanding Guyton's venous return curves

2011 ◽  
Vol 301 (3) ◽  
pp. H629-H633 ◽  
Author(s):  
Daniel A. Beard ◽  
Eric O. Feigl
Keyword(s):  
Cardiac Output ◽  
Blood Volume ◽  
Venous Return ◽  
Systemic Circulation ◽  
Back Pressure ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Right Atrial Pressure ◽  
Simultaneous Increase ◽  
Venous Circulation

Based on observations that as cardiac output (as determined by an artificial pump) was experimentally increased the right atrial pressure decreased, Arthur Guyton and coworkers proposed an interpretation that right atrial pressure represents a back pressure restricting venous return (equal to cardiac output in steady state). The idea that right atrial pressure is a back pressure limiting cardiac output and the associated idea that “venous recoil” does work to produce flow have confused physiologists and clinicians for decades because Guyton's interpretation interchanges independent and dependent variables. Here Guyton's model and data are reanalyzed to clarify the role of arterial and right atrial pressures and cardiac output and to clearly delineate that cardiac output is the independent (causal) variable in the experiments. Guyton's original mathematical model is used with his data to show that a simultaneous increase in arterial pressure and decrease in right atrial pressure with increasing cardiac output is due to a blood volume shift into the systemic arterial circulation from the systemic venous circulation. This is because Guyton's model assumes a constant blood volume in the systemic circulation. The increase in right atrial pressure observed when cardiac output decreases in a closed circulation with constant resistance and capacitance is due to the redistribution of blood volume and not because right atrial pressure limits venous return. Because Guyton's venous return curves have generated much confusion and little clarity, we suggest that the concept and previous interpretations of venous return be removed from educational materials.

New Ultrastructural Observations on Injury and Regeneration of Cilia in Mammalian Conducting Airway Epithelium

1981 ◽  
Vol 39 ◽  
pp. 624-625
Author(s):  
J.L. Carson ◽  
A.M. Collier
Keyword(s):  
Respiratory Tract ◽  
Airway Epithelium ◽  
Defense Mechanisms ◽  
Normal Growth ◽  
Fetal Lung ◽  
Secretory Cells ◽  
Airway Epithelial ◽  
Ciliated Cells ◽  
Conducting Airway ◽  
Conducting Airways

The ciliated cells lining the conducting airways of mammals are integral to the defense mechanisms of the respiratory tract, functioning in coordination with secretory cells in the removal of inhaled and cellular debris. The effects of various infectious and toxic agents on the structure and function of airway epithelial cell cilia have been studied in our laboratory, both of which have been shown to affect ciliary ultrastructure.These observations have led to questions about ciliary regeneration as well as the possible induction of ciliogenesis in response to cellular injury. Classical models of ciliogenesis in the conducting airway epithelium of the mammalian respiratory tract have been based primarily on observations of the developing fetal lung. These observations provide a plausible explanation for the embryological generation of ciliary beds lining the conducting airways but do little to account for subsequent differentiation of ciliated cells and ciliogenesis during normal growth and development.

Parasite defense mechanisms in bees: behavior, immunity, antimicrobials, and symbionts

2019 ◽  
Vol 4 (1) ◽  
pp. 59-76 ◽  
Author(s):  
Alison E. Fowler ◽  
Rebecca E. Irwin ◽  
Lynn S. Adler
Keyword(s):  
Defense Mechanisms ◽  
Poor Quality ◽  
Future Research ◽  
Immune Priming ◽  
Social Bees ◽  
Bee Health ◽  
Landscape Scales ◽  
And Function ◽  
Solitary Species

Parasites are linked to the decline of some bee populations; thus, understanding defense mechanisms has important implications for bee health. Recent advances have improved our understanding of factors mediating bee health ranging from molecular to landscape scales, but often as disparate literatures. Here, we bring together these fields and summarize our current understanding of bee defense mechanisms including immunity, immunization, and transgenerational immune priming in social and solitary species. Additionally, the characterization of microbial diversity and function in some bee taxa has shed light on the importance of microbes for bee health, but we lack information that links microbial communities to parasite infection in most bee species. Studies are beginning to identify how bee defense mechanisms are affected by stressors such as poor-quality diets and pesticides, but further research on this topic is needed. We discuss how integrating research on host traits, microbial partners, and nutrition, as well as improving our knowledge base on wild and semi-social bees, will help inform future research, conservation efforts, and management.

The Dynamics of TAT Process

2014 ◽  
Vol 35 (2) ◽  
pp. 103-133 ◽  
Author(s):  
Benoît Verdon ◽  
Catherine Chabert ◽  
Catherine Azoulay ◽  
Michèle Emmanuelli ◽  
Françoise Neau ◽  
...  
Keyword(s):  
Defense Mechanisms ◽  
Analytical Approach ◽  
Therapeutic Process ◽  
Practice Research ◽  
Rorschach Test ◽  
Mental Functioning ◽  
Projective Tests ◽  
The Subject ◽  
Latent Content ◽  
Rigorous Method

After many years of clinical practice, research and the teaching of projective tests, Shentoub and her colleagues (Debray, Brelet, Chabert & al.) put forward an original and rigorous method of analysis and interpretation of the TAT protocols in terms of psychoanalysis and clinical psychopathology. They developed the TAT process theory in order to understand how the subject builds a narrative. Our article will emphasize the source of the analytical approach developed by V. Shentoub in the 1950s to current research; the necessity of marking the boundary between the manifest and latent content in the cards; the procedure for analyzing the narrative, supported by an analysis sheet for understanding the stories' structure and identifying the defense mechanisms; and how developing hypotheses about how the mental functions are organized, as well as their potential psychopathological characteristics; and the formulation of a diagnosis in psychodynamic terms. In conjunction with the analysis and interpretation of the Rorschach test, this approach allows us to develop an overview of the subject's mental functioning, taking into account both the psychopathological elements that may threaten the subject and the potential for a therapeutic process. We will illustrate this by comparing neurotic, borderline, and psychotic personalities.

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