Time course of phrenic activity and respiratory pressures during airway occlusion in cats

1981 ◽  
Vol 51 (1) ◽  
pp. 99-108 ◽  
Author(s):  
N. M. Siafakas ◽  
H. K. Chang ◽  
M. Bonora ◽  
H. Gautier ◽  
J. Milic-Emili ◽  
...  
Keyword(s):  
Time Course ◽  
Course Development ◽  
Airway Occlusion ◽  
Time Profiles ◽  
Inspiratory Muscles ◽  
Inspiratory Activity ◽  
Proportional Increase ◽  
Relationship Of ◽  
The Relationship ◽  
Hypoxic Mixtures

The morphology of integrated ("moving time average") phrenic electroneurograms (EPHR) and of tracheal (Ptr) and transdiaphragmatic (Pdi) pressure waves during occluded inspirations was studied in eight anesthetized cats breathing air and various hypercapnic and hypoxic mixtures. The shape of the rising part of EPR-, Ptr-, and Pdi-time profiles varied between animals (from convex to concave), but in each animal it remained virtually unchanged by hypoxia and hypercapnia. The shape of the Ptr and Pdi occlusion waves reflected the shape of EPHR. The relationship of EPHR to Pdi and Ptr did not change with chemical drive. It is concluded that central inspiratory activity (CIA) (as reflected by EPHR and its mechanical transforms Pdi and Ptr) increases in amplitude with stimulation of breathing but that the profile of CIA remains essentially unchanged. However, substantial differences in the time course development of phrenic activity, Pdi, and Ptr exist between cats. The fixed interrelationships among EPHR, Pdi, and Ptr indicate a proportional increase in activity among all inspiratory muscles with increased chemical drive.

Mechanism of autograft insufficiency after the Ross operation in children

2012 ◽  
Vol 23 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Motohiko Goda ◽  
Marc Gewillig ◽  
Benedicte Eyskens ◽  
Ruth Heying ◽  
Bjorn Cools ◽  
...  
Keyword(s):  
Aortic Root ◽  
Time Course ◽  
Body Measurements ◽  
Age Group ◽  
Z Score ◽  
Root Reinforcement ◽  
Ross Operation ◽  
Relationship Of ◽  
The Relationship

AbstractBackgroundIt is unclear how autografts grow and dilate after the Ross operation in children. We analysed autograft growth and dilatation in children who underwent the Ross operation and examined the relationship of these factors to autograft failure.MethodsFrom our institutional database, we retrospectively identified 33 children who underwent the Ross operation without aortic root reinforcement (mean age 9.9 years) and had normal body measurements and echocardiographic data throughout follow-up.ResultsAutograft insufficiency developed in 10 patients 5.1 years after the Ross operation. The average Z score at the development of autograft insufficiency was −0.1 (range from −2.0 to 6.1). The proportions of patients who remained free of autograft insufficiency at 5 and 10 years were 87.2% and 55.7%, respectively. A consistent trend in the time course of Z score was not found in any age group studied.ConclusionsAutograft growth and dilation after the Ross operation varied widely among patients, and the incidence of autograft insufficiency was independent of annulus size.

Decay of inspiratory muscle pressure during expiration in anesthetized cats

1983 ◽  
Vol 54 (2) ◽  
pp. 408-413 ◽  
Author(s):  
W. A. Zin ◽  
L. D. Pengelly ◽  
J. Milic-Emili
Keyword(s):  
Respiratory System ◽  
Time Course ◽  
Pentobarbital Sodium ◽  
Airway Occlusion ◽  
Inspiratory Muscles ◽  
Tracheal Pressure ◽  
Resistive Loads ◽  
The Moment ◽  
Spontaneously Breathing

In six spontaneously breathing anesthetized cats (pentobarbital sodium, 35 mg/kg) we studied the antagonistic pressure developed by the inspiratory muscles during expiration (PmusI). This was accomplished in two ways: 1) with our previously reported method (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 52: 1266–1271, 1982) based on the measurement of changes in lung volume and airflow during spontaneous expiration, together with determination of the total passive respiratory system elastance and resistance; and 2) measurement of the time course of changes in tracheal/pressure after airway occlusion at end inspiration, up to the moment when the inspiratory muscles become completely relaxed. The agreement between the two methods is generally good, both in the amplitude of PmusI and in its time course. We also applied the first method to spontaneous expirations through added linear resistive loads. These did not alter the relative decay of PmusI. Thus in anesthetized cats the braking action of the inspiratory muscles does not decrease when expiratory resistive loads are added, i.e., when such braking is clearly not required.

Coupling of GnRH Concentration and the GnRH Receptor-Activated Gene Program

2002 ◽  
Vol 16 (6) ◽  
pp. 1145-1153 ◽  
Author(s):  
Tony Yuen ◽  
Elisa Wurmbach ◽  
Barbara J. Ebersole ◽  
Frederique Ruf ◽  
Robert L. Pfeffer ◽  
...  
Keyword(s):  
Time Course ◽  
Nuclear Protein ◽  
Gene Induction ◽  
Gnrh Receptor ◽  
Quantitative Real Time Pcr ◽  
Number Of Genes ◽  
Lag Times ◽  
Complex Signaling ◽  
Relationship Of ◽  
The Relationship

Abstract The initial waves of gene induction caused by GnRH in the LβT2 gonadotrope cell line have recently been identified using microarrays. We now investigate the relationship of the concentration of GnRH to the level of biosynthesis induced. Using an optimized custom cDNA microarray, we show that a large number of genes are induced in a concentration-dependent fashion. Detailed time course studies of the induction of six induced transcripts using quantitative real-time PCR suggest that the amplitude, but not the temporal pattern, depends on the concentration of GnRH. The early genes appear to show a delay in gene induction, followed by a linear phase of increase. The relationship of rate of synthesis and GnRH concentration was studied by mathematical modeling of the induction of two genes, gly96 and tis11. In both cases, only the rates of increase, but not the lag times, are influenced by the concentration of GnRH exposure. Western blot analyses for c-Jun and Egr1 show that the levels of nuclear protein for these transcription factors also depend on the concentration of GnRH. These studies indicate that, despite the complex signaling network connecting the receptor to the activated genes, the biosynthetic rate of RNA polymerase at induced genes is correlated with the concentration of GnRH at the GnRH receptor.

Respiratory effects of progressive asphyxia in rabbit pups and adult rabbits

1984 ◽  
Vol 56 (4) ◽  
pp. 940-947 ◽  
Author(s):  
T. Trippenbach ◽  
R. Affleck ◽  
G. Kelly
Keyword(s):  
Time Course ◽  
Age Groups ◽  
Esophageal Pressure ◽  
Muscle Dysfunction ◽  
Respiratory Drive ◽  
Similar Time ◽  
Airway Occlusion ◽  
Temporal Relationships ◽  
Central Inspiratory Activity ◽  
Inspiratory Activity

Effects of prolonged airway occlusion were investigated in anesthetized and vagotomized 9-to 15-day-old pups and adult rabbits. The changes and temporal relationships between “integrated” phrenic activity, external intercostal electromyogram (INT), and esophageal pressure (Pes) were examined. Each occlusion resulted in hyperpnea, apnea, and gasping. Blood pressure recorded during the occlusion showed a marked decrease. During hyperpnea, the rate of changes and maximal amplitudes in Pes and INT were similar in both age groups. The increase in integrated phrenic activity (PHR) was significantly greater in young rabbits. In both age groups, changes in INT during gasping followed a similar time course and exceeded those in PHR. Maximal values of the three parameters were concurrent in adults, whereas the increase in INT peaked later than PHR and Pes in rabbit pups. In adult rabbits, PHR, INT, and Pes, during the last gasp, decreased to the values of the first hyperpnea breath. In rabbit pups, Pes of the last gasp decreased significantly below this value while INT was still elevated. This Pes decrease could result from inspiratory muscle dysfunction in the pups. Thus in rabbit pups, 1) greater changes in PHR were necessary to produce a given change in Pes than in adult rabbits; 2) activity of the external intercostal muscles was not efficient in developing pressure under conditions of asphyxia; and 3) the independent activation of diaphragmatic and intercostal motoneurons is not of vagal origin. Additionally, the results led us to conclude that Pes can serve as a close approximation of respiratory drive in adult rabbits. This parameter, however, cannot be used as an index of central inspiratory activity during gasping in rabbit pups.

Relationship of thoracic volume and airway occlusion pressure: muscular effects

1977 ◽  
Vol 43 (2) ◽  
pp. 312-321 ◽  
Author(s):  
F. L. Eldridge ◽  
K. Z. Vaughn
Keyword(s):  
Airway Pressure ◽  
Respiratory Control ◽  
Muscle Performance ◽  
Occlusion Pressure ◽  
Force Output ◽  
Airway Occlusion ◽  
Inspiratory Muscles ◽  
Airway Occlusion Pressure ◽  
Spontaneously Breathing ◽  
Relationship Of

The occluded airway pressure generated by contraction of inspiratory muscles was measured in spontaneously breathing, anesthetized, vagotomized cats at thoracic volumes below, at, and above true FRC (range, -8 to +28 ml/kg). A relatively constant neural drive at all volumes was shown by recordings of integrated phrenic nerve and external intercostal muscle activities. Peak occlusion pressure declined progressively with increasing thoracic volume and increased with occlusion volumes below FRC. Occlusion pressures measured early in inspiration (0.3 and 0.5 s) decreased similarly. Since occluded airway pressure was a satisfactory index of muscle force output of all inspiratory muscles, the study demonstrates that inspiratory muscle performance decreases with increasing thoracic volume throughout the range studied. Analysis of all occluded breaths shows that, quantitatively, the decline in muscle performance from that occurring at true FRC was -1.9% per ml/kg volume change from FRC. Zero effective muscle pressure generation occurred at 52 ml/kg above FRC, or 2.8 times FRC. These findings have important implications for the use of occlusion pressures and ventilatory responses in respiratory control system studies, since changes in FRC may affect muscle performance.

scholarly journals The reciprocal relationship of thrombopoietin (c-Mpl ligand) to changes in the platelet mass during busulfan-induced thrombocytopenia in the rabbit

Blood ◽  
1995 ◽  
Vol 85 (10) ◽  
pp. 2720-2730 ◽  
Author(s):  
DJ Kuter ◽  
RD Rosenberg
Keyword(s):  
Time Course ◽  
Blood Platelets ◽  
Subcutaneous Administration ◽  
Reciprocal Relationship ◽  
Blood Levels ◽  
Relationship Of ◽  
The Relationship ◽  
Platelet Count Nadir ◽  
Platelet Mass

Thrombopoietin (c-Mpl ligand) has recently been purified and is considered to be the humoral regulator of platelet production. To see whether this molecule possessed the physiologic characteristics necessary to mediate the feed-back loop between blood platelets and the bone marrow megakaryocytes, we determined the relationship between blood levels of thrombopoietin and changes in the circulating platelet mass. We developed a model of nonimmune thrombocytopenia in rabbits by the subcutaneous administration of busulfan. Compared with pretreatment plasma, plasma taken from all thrombocytopenic rabbits at their platelet nadir contained increased amounts of thrombopoietin. All of this activity was neutralized by soluble c-Mpl receptor. We subsequently measured the level of thrombopoietin in the circulation over the entire time course after the administration of busulfan. As the platelet mass declined, levels of thrombopoietin increased inversely and proportionally and peaked during the platelet nadir. With return of the platelet mass toward normal, thrombopoietin levels decreased accordingly. When platelets were transfused into thrombocytopenic rabbits near the time of their platelet count nadir, the elevated levels of thrombopoietin decreased. In addition, platelets were observed to remove thrombopoietin from thrombocytopenic plasma in vitro. These results confirm that thrombopoietin is the humoral mediator of megakaryocytopoiesis and suggest that the platelet mass may directly play a role in regulating the circulating levels of this factor.

scholarly journals Google-Reflected Information on Drugs Used for Anesthesia: Time Course of Growth in Number of Web Pages

2021 ◽  
Author(s):  
Kamen V. Vlassakov ◽  
Igor Kissin
Keyword(s):  
Time Course ◽  
General Information ◽  
Web Pages ◽  
General Anesthetics ◽  
Related Information ◽  
Academic Medical ◽  
Pubmed Database ◽  
Academic Information ◽  
Relationship Of ◽  
The Relationship

Abstract Purpose: The aim of this study was to determine the time course of growth in general Google-reflected information on drugs used for anesthesia. As a contrast to the changes in general Google-reflected information we used the changes in academic PubMed-reflected information.Methods: General Google-reflected information on anesthetics was assessed by counting the number of Google Web pages. Academic information was assessed by counting the number of articles in medico-biological journals covered by the PubMed database (The National Library of Medicine). The ratio of Google Web pages to PubMed articles (G/P Ratio) was used to indicate prevalence of Google-related information. Twenty-five agents used for anesthesia were selected from three pharmacological groups – general anesthetics, local anesthetics, and opioids -- based on the frequency of their association with anesthesia in academic medical journals. The time course of growth in general Google-reflected information was determined for seven 5-year periods, from 1983 to 2017. Results: With the growing role of the Web, the number of Google Web pages on drugs used for anesthesia increased rapidly. As a result, the relationship between general Google-reflected and academic PubMed-reflected information on anesthetics profoundly changed. Before the 1993-1997 period, the number of Google Web pages on anesthetics was only a fraction of the number of PubMed articles. By the 2013-2017period, the relationship was completely reversed: for any anesthetic, the number of Google Web pages was at least three times greater than the number of PubMed articles. However, the relationship of general Web-related information and academic information with different anesthetics was very variable. In 2013-2017, the G/P Ratio, indicating the magnitude of general information dominance, for the 25 agents varied from 3.0 (remifentanil) to 23.2 (oxycodone). The dominance of Google information was especially profound with drugs that have a wider spectrum of possible use beyond the field of anesthesia, such as oxycodone or diazepam.Conclusion: General Google-reflected information is rapidly growing and, as a result, its dominance over academic PubMed-reflected information is constantly increasing.

Auxotonic contractions in cardiac muscle segments

1979 ◽  
Vol 237 (2) ◽  
pp. H131-H138 ◽  
Author(s):  
L. L. Huntsman ◽  
D. S. Joseph ◽  
M. Y. Oiye ◽  
G. L. Nichols
Keyword(s):  
Time Course ◽  
Segment Length ◽  
Cross Sectional ◽  
Visual Markers ◽  
Induction Technique ◽  
Central Regions ◽  
Relationship Of ◽  
Muscle Cross Sectional Area ◽  
The Relationship ◽  
Whole Muscle

The dynamics of segment shortening have been measured in the central regions of isolated papillary muscles during muscle isometric and after-loaded isotonic contractions. Segment lengths are inferred from muscle cross-sectional area using an assumption that the segments remain isovolumic. Area is assessed with a magnetic induction technique. Infused microspheres have been used as visual markers to corroborate the segment length measurement. The results confirm the existence of major segmental shortening during muscle isometric conditions. However, the time course of shortening is not the same as that of force development. Rather, the segments remain shortened until after force has fallen significantly from its peak value. This behavior appears in the force-segment length plane as counterclockwise loops. The relationship of peak force to segment length has been determined and found to depend on the mechanical conditions under which the muscle is equilibrated. These results demonstrate the utility of the new technique and indicate central segment behavior that is substantially different from that observed for the whole muscle.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

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