scholarly journals Inhibitory control of active expiration by the Bötzinger complex in rats

2019 ◽  
Author(s):  
Karine C. Flor ◽  
William H. Barnett ◽  
Marlusa Karlen-Amarante ◽  
Yaroslav Molkov ◽  
Daniel B. Zoccal
Keyword(s):  
Short Term ◽  
Inhibitory Circuitry ◽  
Respiratory Network ◽  
Bötzinger Complex ◽  
Expiratory Neurons ◽  
Parafacial Respiratory Group ◽  
And Control ◽  
Pharmacological Manipulations ◽  
Sustained Hypoxia

ABSTRACTThe expiratory neurons of the Bötzinger complex (BötC) provide inhibitory inputs to the respiratory network, which, during eupnea, are critically important for respiratory phase transition and duration control. Herein, we investigated how the BötC neurons interact with the expiratory oscillator located in the parafacial respiratory group (pFRG) and control the abdominal activity during active expiration. Using the decerebrated, arterially perfused in situ rat preparations, we recorded the neuronal activity and performed pharmacological manipulations of the BötC and pFRG during hypercapnia or after the exposure to short-term sustained hypoxia – conditions that generate active expiration. The experimental data were integrated in a mathematical model to gain new insights in the inhibitory connectome within the respiratory central pattern generator. Our results reveal a complex inhibitory circuitry within the BötC that provides inhibitory inputs to the pFRG thus restraining abdominal activity under resting conditions and contributing to abdominal expiratory pattern formation during active expiration.

Sand grain mineralogy and morphology under forest and grassland/arable fields in Eastern Hungary

2014 ◽  
Vol 63 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Kitti Balog ◽  
L. Kuti ◽  
A. Szabó ◽  
T. Tóth
Keyword(s):  
Arable Land ◽  
Soil Layer ◽  
Size Fraction ◽  
Sandy Soils ◽  
Short Term ◽  
Etch Pits ◽  
Arable Fields ◽  
And Control ◽  
Hungarian Plain

Related to ongoing (re)forestation in the Great Hungarian Plain the short-term influence of changing land cover was studied on the grains of skeletal sandy soils. In three sampling areas with forest and grassy/arable control plots, the 0.1–0.2 mm grain size fraction of samples taken every 20 cm from the 0–100 cm sandy soil layer (totalling 22,509 grains) were separated and described with optical mineralogical microscope. In order to distinguish sand grains of forest-covered and control areas (grassland/arable land), the results of mineralogical and morphological observations were compared. It was revealed that the amount of feldspar grains is 8–9 times less than the amount of the quartz ones. The increase in the quartz/feldspar (q/fp) ratio is tied to the “consumption” of feldspars: the intense consumption of potassium by trees. Under the forest-covered fields, the number of in-situ crushed grains increased. Grains with etch pits are frequent in samples from the grasslands (except in Hajdúsámson). In samples of forest-covered areas a greatly increased number of brown grains with limonite and/or humus films were observed. The gained results can be useful in proving earlier land use in forested fields.

scholarly journals Heartbeats entrain breathing via baroreceptor-mediated modulation of expiratory activity

2020 ◽  
Author(s):  
William H. Barnett ◽  
David M. Baekey ◽  
Julian F. R. Paton ◽  
Thomas E. Dick ◽  
Erica A. Wehrwein ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Pressure Pulse ◽  
Perfusion Pressure ◽  
Deep Breathing ◽  
Breathing Patterns ◽  
Transient Pressure ◽  
Respiratory Network ◽  
Expiratory Neurons ◽  
Male Subjects

AbstractCardio-ventilatory coupling refers to a heartbeat (HB) occurring at a preferred latency before the onset of the next breath. We hypothesized that the pressure pulse generated by a HB activates baroreceptors that modulates brainstem expiratory neuronal activity and delays the initiation of inspiration. In supine male subjects, we recorded ventilation, electrocardiogram, and blood pressure during 20-min epochs of baseline, slow-deep breathing, and recovery. In in situ rodent preparations, we recorded brainstem activity in response to pulses of perfusion pressure. We applied a well-established respiratory network model to interpret these data. In humans, the latency between HBs and onset of inspiration was consistent across different breathing patterns. In in situ preparations, a transient pressure pulse during expiration activated a subpopulation of expiratory neurons normally active during post-inspiration; thus, delaying the next inspiration. In the model, baroreceptor input to post-inspiratory neurons accounted for the effect. These studies are consistent with baroreflex activation modulating respiration through a pauci-synaptic circuit from baroreceptors to onset of inspiration.

scholarly journals Short-Term Photochemical and Biological Unreactivity of Macrophyte-Derived Dissolved Organic Matter in a Subtropical Shallow Lake

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Ng Haig They ◽  
David Motta Marques ◽  
Rafael Siqueira Souza ◽  
Lúcia Ribeiro Rodrigues
Keyword(s):  
Light Exposure ◽  
Mechanistic Explanation ◽  
Bacterial Density ◽  
Water Color ◽  
Short Term ◽  
Uv Irradiance ◽  
Littoral Zones ◽  
Combined Control ◽  
And Control

Macrophytes have been associated with low bacterial metabolism in the littoral zones of lake Mangueira, but an explanation for this pattern is largely unknown. In this study, macrophyte-derived DOM was incubated in situ for the measurement of the effect of grazers, bacteria, and light on its degradation in three experiments. The water was separated in bulk, bacterial, and control (+ HgCl2) fractions and exposed to or hidden from sunlight for 120 h. Unchange in bacterial variables in the bulk fraction suggested a combined control of radiation and grazing on bacteria. Light treatment increased bacterial density but not biomass and biovolume, while bacterial density decreased in the dark. Significant fading of water color in the bacterial fraction only occurred after light exposure, indicating a complementary pathway of light and bacteria. DOC and the Abs250 : 365 ratio did not change with incubation, indicating no net change of DOC pool and reactivity. Due to continuous carbon loading from macrophytes and low UV irradiance, the very low rates of DOM degradation provide the mechanistic explanation for the observed impacts of macrophytes in lake’s carbon metabolism in littoral zones.

scholarly journals Interaction between the retrotrapezoid nucleus and the parafacial respiratory group to regulate active expiration and sympathetic activity in rats

2018 ◽  
Vol 315 (5) ◽  
pp. L891-L909 ◽  
Author(s):  
Daniel B. Zoccal ◽  
Josiane N. Silva ◽  
William H. Barnett ◽  
Eduardo V. Lemes ◽  
Barbara Falquetto ◽  
...  
Keyword(s):  
Sympathetic Activity ◽  
Sympathetic Nerves ◽  
Adult Rats ◽  
Retrotrapezoid Nucleus ◽  
Respiratory Network ◽  
Interacting Populations ◽  
Neurokinin 1 ◽  
Parafacial Respiratory Group ◽  
Excitatory Drive

The retrotrapezoid nucleus (RTN) contains chemosensitive cells that distribute CO2-dependent excitatory drive to the respiratory network. This drive facilitates the function of the respiratory central pattern generator (rCPG) and increases sympathetic activity. It is also evidenced that during hypercapnia, the late-expiratory (late-E) oscillator in the parafacial respiratory group (pFRG) is activated and determines the emergence of active expiration. However, it remains unclear the microcircuitry responsible for the distribution of the excitatory signals to the pFRG and the rCPG in conditions of high CO2. Herein, we hypothesized that excitatory inputs from chemosensitive neurons in the RTN are necessary for the activation of late-E neurons in the pFRG. Using the decerebrated in situ rat preparation, we found that lesions of neurokinin-1 receptor-expressing neurons in the RTN region with substance P-saporin conjugate suppressed the late-E activity in abdominal nerves (AbNs) and sympathetic nerves (SNs) and attenuated the increase in phrenic nerve (PN) activity induced by hypercapnia. On the other hand, kynurenic acid (100 mM) injections in the pFRG eliminated the late-E activity in AbN and thoracic SN but did not modify PN response during hypercapnia. Iontophoretic injections of retrograde tracer into the pFRG of adult rats revealed labeled phox2b-expressing neurons within the RTN. Our findings are supported by mathematical modeling of chemosensitive and late-E populations within the RTN and pFRG regions as two separate but interacting populations in a way that the activation of the pFRG late-E neurons during hypercapnia require glutamatergic inputs from the RTN neurons that intrinsically detect changes in CO2/pH.

A computer-control program for TEM in situ fatigue experiments

1989 ◽  
Vol 47 ◽  
pp. 620-621
Author(s):  
Kenneth S. Vecchio ◽  
John A. Hunt
Keyword(s):  
Slow Crack Growth ◽  
Computer Control ◽  
Control Program ◽  
Video Tape ◽  
Computer Control System ◽  
Transmission Electron ◽  
In Situ Experiments ◽  
Tremendous Amount ◽  
And Control

In-situ experiments conducted within a transmission electron microscope provide the operator a unique opportunity to directly observe microstructural phenomena, such as phase transformations and dislocation-precipitate interactions, “as they happen”. However, in-situ experiments usually require a tremendous amount of experimental preparation beforehand, as well as, during the actual experiment. In most cases the researcher must operate and control several pieces of equipment simultaneously. For example, in in-situ deformation experiments, the researcher may have to not only operate the TEM, but also control the straining holder and possibly some recording system such as a video tape machine. When it comes to in-situ fatigue deformation, the experiments became even more complicated with having to control numerous loading cycles while following the slow crack growth. In this paper we will describe a new method for conducting in-situ fatigue experiments using a camputer-controlled tensile straining holder.The tensile straining holder used with computer-control system was manufactured by Philips for the Philips 300 series microscopes. It was necessary to modify the specimen stage area of this holder to work in the Philips 400 series microscopes because the distance between the optic axis and holder airlock is different than in the Philips 300 series microscopes. However, the program and interfacing can easily be modified to work with any goniometer type straining holder which uses a penrmanent magnet motor.

scholarly journals The Importance of Interphases in Energy Storage Devices: Methods and Strategies to Investigate and Control Interfacial Processes

Physchem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 26-44
Author(s):  
Chiara Ferrara ◽  
Riccardo Ruffo ◽  
Piercarlo Mustarelli
Keyword(s):  
Energy Storage ◽  
Solid Electrolyte Interphase ◽  
Lithium Ion ◽  
Lithium Metal ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Lithium Metal Batteries ◽  
And Control ◽  
Near Future

Extended interphases are playing an increasingly important role in electrochemical energy storage devices and, in particular, in lithium-ion and lithium metal batteries. With this in mind we initially address the differences between the concepts of interface and interphase. After that, we discuss in detail the mechanisms of solid electrolyte interphase (SEI) formation in Li-ion batteries. Then, we analyze the methods for interphase characterization, with emphasis put on in-situ and operando approaches. Finally, we look at the near future by addressing the issues underlying the lithium metal/electrolyte interface, and the emerging role played by the cathode electrolyte interphase when high voltage materials are employed.

scholarly journals Bioimpedance Guided Fluid Management in Peritoneal Dialysis

2020 ◽  
Vol 15 (5) ◽  
pp. 685-694 ◽  
Author(s):  
Na Tian ◽  
Xiao Yang ◽  
Qunying Guo ◽  
Qian Zhou ◽  
Chunyan Yi ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Patient Survival ◽  
Fluid Management ◽  
Volume Overload ◽  
Short Term ◽  
Cardiovascular Disease Mortality ◽  
Technique Survival ◽  
Disease Mortality ◽  
Clinical Methods ◽  
And Control

Background and objectivesBioelectrical impedance analysis (BIA) devices can help assess volume overload in patients receiving maintenance peritoneal dialysis. However, the effects of BIA on the short-term hard end points of peritoneal dialysis lack consistency. This study aimed to test whether BIA-guided fluid management could improve short-term outcomes in patients on peritoneal dialysis.Design, setting, participants, & measurementsA single-center, open-labeled, randomized, controlled trial was conducted. Patients on prevalent peritoneal dialysis with volume overload were recruited from July 1, 2013 to March 30, 2014 and followed for 1 year in the initial protocol. All participants with volume overload were 1:1 randomized to the BIA-guided arm (BIA and traditional clinical methods) and control arm (only traditional clinical methods). The primary end point was all-cause mortality and secondary end points were cardiovascular disease mortality and technique survival.ResultsA total of 240 patients (mean age, 49 years; men, 51%; diabetic, 21%, 120 per group) were enrolled. After 1-year follow-up, 11(5%) patients died (three in BIA versus eight in control) and 21 patients were permanently transferred to hemodialysis (eight in BIA versus 13 in control). The rate of extracellular water/total body water decline in the BIA group was significantly higher than that in the control group. The 1-year patient survival rates were 96% and 92% in BIA and control groups, respectively. No significant statistical differences were found between patients randomized to the BIA-guided or control arm in terms of patient survival, cardiovascular disease mortality, and technique survival (P>0.05).ConclusionsAlthough BIA-guided fluid management improved the fluid overload status better than the traditional clinical method, no significant effect was found on 1-year patient survival and technique survival in patients on peritoneal dialysis.

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