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Respiratory Physiology & Neurobiology

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https://www.readbyqxmd.com/read/28088638/the-dlno-dlco-ratio-physiological-significance-and-clinical-implications
#1
J M B Hughes, A T Dinh-Xuan
DLNO/DLCO directly measures the ratio of the diffusing capacities of the lung for nitric oxide (NO) and carbon monoxide (CO). In terms of the Roughton and Forster, 1957; equation, 1/DL=1/Dm+1/θVc, where Dm is the membrane (Dm) and θVc is the red cell component of the overall diffusing conductance (DL), DLNO mostly reflects the Dm component and DLCO the θVc red cell component. The DLNO/DLCO ratio is positively related to the DmCO/Vc ratio and the CO red cell resistance (1/θCOVc) as a percentage of the total resistance (1/DLCO), independent of the absolute values of DLNO or DLCO...
January 11, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28087341/lung-diffusing-capacity-in-sub-saharan-africans-versus-european-caucasians
#2
Bamodi Simaga, Kevin Forton, Yoshiki Motoji, Robert Naeije, Vitalie Faoro
Single breath measurements of lung diffusing capacity (DL) for carbon monoxide (CO) and nitric oxide (NO) were performed in age-, sex-, weight- and height-matched 32 Sub-Saharan Africans (13 women) and 32 Caucasian Europeans, and repeated in 14 of each group at 80% of maximum exercise capacity. In Africans versus Caucasians respectively, DLNO was 153±31 vs 176±38ml/mmHg/min at rest (P<0.001) and 210±48 vs 241±52ml/mmHg/min at exercise (P<0.01) while hemoglobin-adjusted DLCO was 29±6 vs 34±6ml/mmHg/min at rest (P<0...
January 10, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28087340/electrophysiological-alterations-in-diaphragm-muscle-caused-by-abdominal-ischemia-reperfusion
#3
Seckin Tuncer, Nizamettin Dalkilic, Ilksen Burat
Ischemia-reperfusion injury is the major complication of abdominal aortic surgery, and it mainly affects the lower extremities and remote organs. In the present study, the electrophysiological alterations in diaphragm that underlie the post-operative respiratory dysfunction were investigated. Wistar Albino rats were randomly divided into two groups: SHAM (only laparotomy was performed) and IR (abdominal aorta was clamped for 30min and reperfused for 2h). Following the operational period diaphragm muscles were isolated and electrophysiological experiments were carried out in-vitro...
January 10, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28082171/abdominal-muscle-activity-during-breathing-in-different-postures-in-copd-stage-0-and-healthy-subjects
#4
António Mesquita Montes, Joana Maia, Carlos Crasto, Cristina Argel de Melo, Paulo Carvalho, Rita Santos, Susana Pereira, João Paulo Vilas-Boas
This study aims to evaluate the effect of different postures on the abdominal muscle activity during breathing in subjects "at risk" for the development of chronic obstructive pulmonary disease (COPD) and healthy. Twenty-nine volunteers, divided in "At Risk" for COPD (n=16; 47.38±5.08years) and Healthy (n=13; 47.54±6.65years) groups, breathed at the same rhythm in supine, standing, tripod and 4-point-kneeling positions. Surface electromyography was performed to assess the activation intensity of rectus abdominis, external oblique and transversus abdominis/internal oblique (TrA/IO) muscles, during inspiration and expiration...
January 7, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28057577/heterogeneity-of-blood-flow-and-metabolism-during-exercise-in-patients-with-chronic-obstructive-pulmonary-disease
#5
Zafeiris Louvaris, Helmut Habazettl, Andreas Asimakos, Harrieth Wagner, Spyros Zakynthinos, Peter D Wagner, Ioannis Vogiatzis
The study investigated whether the capacity to regulate muscle blood flow (Q) relative to metabolic demand (VO2) is impaired in COPD. Using six NIRS optodes over the upper, middle and lower vastus lateralis in 6 patients, (FEV1:46±12%predicted) we recorded from each: a) Q by indocyanine green dye injection, b) VO2/Q ratios based on fractional tissue O2 saturation and c) VO2 as their product, during constant-load exercise (at 20%, 50% and 80% of peak capacity) in normoxia and hyperoxia (FIO2:1.0). At 50 and 80%, relative dispersion (RD) for Q, but not for VO2, was greater in normoxia (0...
January 3, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28057576/a-stochastic-and-integrative-model-of-breathing
#6
Brett F BuSha, George Banis
Human breathing patterns contain both temporal scaling characteristics, and an innately random component. A stochastic and mathematically integrative model of breathing (SIMB) that simulated the natural random and fractal-like pattern of human breathing was designed using breath-to-breath interval (BBI) data recorded from 14 healthy subjects. Respiratory system memory was estimated with autocorrelation, and a probability density function (PDF) was created by fitting a polynomial curve to each normalized BBI sequence histogram...
January 3, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28049017/the-roughton-forster-equation-for-dlco-and-dlno-re-examined
#7
M-Y Kang, D Grebenkov, H Guénard, I Katz, B Sapoval
Roughton and Forster (RF) proposed to split the lung diffusing capacity into two contributions describing first, diffusion to red blood cells (RBC), and second, capture by diffusion from the RBC surface and reaction with haemoglobin. Solving the diffusion-reaction equations for simplified capillary-RBC structures, we investigate the RF interpretation. This reveals first that the conventional extrapolation to zero pressure of 1/DLCO on PO2 is not a correct measure of the diffusive component. Consequently the capillary volumes deduced from this extrapolation are erroneous...
December 31, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28041993/efficient-breathing-at-neonatal-ages-a-sex-and-epo-dependent-issue
#8
REVIEW
Pablo Iturri, Aida Bairam, Jorge Soliz
During postnatal life, the respiratory control system undergoes intense development and is highly responsive to stimuli emerging from the environment. In fact, interruption of breathing prevents gas exchange and results in systemic hypoxia that, if prolonged, can lead to cardio-respiratory failure or sudden infant death. Moreover, in newborns and infants, respiratory disorders related to neural control dysfunction show significant sexual dimorphism with a higher prevalence in males. To this day, the therapeutic tools available to alleviate these respiratory disorders remain limited...
December 29, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28040523/impact-of-arousal-threshold-and-respiratory-effort-on-the-duration-of-breathing-events-across-sleep-stage-and-time-of-night
#9
Soheeb A Wains, Mohamad El-Chami, Ho-Sheng Lin, Jason H Mateika
PURPOSE: The frequency and duration of breathing events are influenced by sleep stage and time of day. In the present study we examined if these modifications are linked to adaptations in the arousal threshold and/or the magnitude of respiratory effort during and immediately after breathing events. METHODS: Participants with sleep apnea slept for 3h in the evening and morning. For breathing events detected during these sessions the rate of change of respiratory effort, maximum respiratory effort immediately prior to termination of an event, and the maximum tidal volume and the minimum partial pressure of end-tidal carbon dioxide (PETCO2) immediately following an event were measured...
December 28, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28034711/ventilatory-and-chemoreceptor-responses-to-hypercapnia-in-neonatal-rats-chronically-exposed-to-moderate-hyperoxia
#10
Ryan W Bavis, Ke-Yong Li, Kathryn J DeAngelis, Ryan J March, Josefine A Wallace, Sarah Logan, Robert W Putnam
Rats reared in hyperoxia hypoventilate in normoxia and exhibit progressive blunting of the hypoxic ventilatory response, changes which are at least partially attributed to abnormal carotid body development. Since the carotid body also responds to changes in arterial CO2/pH, we tested the hypothesis that developmental hyperoxia would attenuate the hypercapnic ventilatory response (HCVR) of neonatal rats by blunting peripheral and/or central chemoreceptor responses to hypercapnic challenges. Rats were reared in 21% O2 (Control) or 60% O2 (Hyperoxia) until studied at 4, 6-7, or 13-14days of age...
December 26, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28027938/superimposed-pressure-oscillations-an-alternative-to-treat-airway-hyperresponsiveness-in-an-acute-sensitized-airways-mouse-model
#11
M J Jo-Avila, A M Al-Jumaily
The main driving mechanism during an asthma attack is the hyper-constrictions of airway smooth muscle (ASM), which reduces the airway lumen and makes normal breathing difficult. In spite of some noticeable side effects, bronchodilator drugs such as salbutamol are used to alleviate these symptoms by inducing temporary relaxation of the contracted ASM. In vitro studies have shown that mechanical oscillation can induce relaxation in isolated contracted ASM obtained from healthy subjects but not from asthmatics...
December 24, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28017906/distensibility-index-of-the-inferior-vena-cava-in-experimental-acute-respiratory-distress-syndrome
#12
R Mendes, M V Oliveira, G A Padilha, R S Santos, N N Rocha, R R Luiz, M G Abreu, P Pelosi, P R M Rocco, P L Silva
We determined the accuracy of distensibility index of inferior vena cava (dIVC) for evaluation of fluid responsiveness in rats with acute respiratory distress syndrome (ARDS) and validated this index for use in rat models. In protocol 1, E. coli lipopolysaccharide was administered in Wistar rats (n=7). After 24h, animals were mechanically ventilated, and stroke volume (SV) and dIVC quantified after blood drainage and subsequent volume expansion (albumin 20%). A receiver operating characteristic (ROC) curve was plotted to determine the optimal dIVC cutoff...
December 23, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28013061/voltage-and-receptor-mediated-activation-of-a-non-selective-cation-channel-in-rat-carotid-body-glomus-cells
#13
Jiaju Wang, James O Hogan, Donghee Kim
A recent study showed that hypoxia activates a Ca(2+)-sensitive, Na(+)-permeable non-selective cation channel (NSC) in carotid body glomus cells. We studied the effects of mitochondrial inhibitors that increase Ca(2+) influx via Ca(2+) channel (Cav), and receptor agonists that release Ca(2+) from endoplasmic reticulum (ER) on NSC. Mitochondrial inhibitors (NaCN, FCCP, H2S, NO) elevated [Ca(2+)]i and activated NSC. Angiotensin II and acetylcholine that elevate [Ca(2+)]i via the Gq-IP3 pathway activated NSC. However, endothelin-1 (Gq) and 5-HT (Gq) showed little or no effect on [Ca(2+)]i and did not activate NSC...
December 21, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28013060/the-blood-transfer-conductance-for-nitric-oxide-infinite-vs-finite-%C3%AE-no
#14
Kirsten E Coffman, Steven C Chase, Bryan J Taylor, Bruce D Johnson
Whether the specific blood transfer conductance for nitric oxide (NO) with hemoglobin (θNO) is finite or infinite is controversial but important in the calculation of alveolar capillary membrane conductance (DmCO) and pulmonary capillary blood volume (VC) from values of lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO). In this review, we discuss the background associated with θNO, explore the resulting values of DmCO and VC when applying either assumption, and investigate the mathematical underpinnings of DmCO and VC calculations...
December 21, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28013059/role-of-gender-in-basic-cough-research
#15
Jana Plevkova, Tomas Buday, Natalia Kavalcikova Bogdanova, Lea Kovacikova, Robert Ruzinak
Cough hypersensitivity affects mainly postmenopausal women. Pathogenesis remains unknown in their case; therefore, an optimal treatment is unavailable. Only male guinea pigs are used in basic cough research and exclusion of females leads to gender bias. Nowadays, the efforts of grant agencies aim to support projects which take gender into account and involve both sexes to reduce gender bias. The aim of our pilot study is to assess the suitability of female guinea pig model in cough research. Cough response to citric acid (0...
December 21, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28013058/leg-compressions-improve-ventilatory-efficiency-while-reducing-peak-and-post-exercise-blood-lactate-but-does-not-improve-perceived-exertion-exercise-economy-or-aerobic-exercise-capacity-in-endurance-trained-runners
#16
Eric Rivas, John D Smith, Nestor W Sherman
PURPOSE: The objective of this study was to determine if leg compressions would alter cardiorespiratory and perceived exertion measures during rest, submaximal and maximal exercise in endurance-trained runners. METHOD: Thirteen young, endurance trained runners (10 males, 20.9±3y, 58.9±5.7mlkgmin(-1)) completed a randomized design, leg compressions and non-compression control condition. The incremental graded exercise test consisted of baseline rest and submaximal intensities at 23%, 70%, 75%, 85% and then a progressive increase to 100% VO2max...
December 21, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28013057/neural-control-of-ventilation-prevents-both-over-distension-and-de-recruitment-of-experimentally-injured-lungs
#17
Lukas Brander, Onnen Moerer, Göran Hedenstierna, Jennifer Beck, Jukka Takala, Arthur S Slutsky, Christer Sinderby
BACKGROUND: Endogenous pulmonary reflexes may protect the lungs during mechanical ventilation. We aimed to assess integration of continuous neurally adjusted ventilatory assist (cNAVA), delivering assist in proportion to diaphragm's electrical activity during inspiration and expiration, and Hering-Breuer inflation and deflation reflexes on lung recruitment, distension, and aeration before and after acute lung injury (ALI). METHODS: In 7 anesthetised rabbits with bilateral pneumothoraces, we identified adequate cNAVA level (cNAVAAL) at the plateau in peak ventilator pressure during titration procedures before (healthy lungs with endotracheal tube, [HLETT]) and after ALI (endotracheal tube [ALIETT] and during non-invasive ventilation [ALINIV])...
December 21, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/27956213/sex-differences-in-cough-reflex
#18
J Plevkova, T Buday, N Kavalcikova-Bogdanova, I Ioan, S Demoulin-Alexikova
Majority of patients visiting cough clinics are postmenopausal women, who are affected by intractable cough for years. Why the cough reflex becomes exaggerated in women is not known. Basic research excludes females from the studies contributing to the sex bias which may be responsible for lack of understanding of "hypersensitive" cough in women. Biological and behavioural differences between women and men are the factors affecting cough physiology. Gender also shapes the patterns of behaviour and determines the character of environmental exposures which differs between sexes...
December 9, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/27916736/the-history-of-the-pulmonary-diffusing-capacity-for-nitric-oxide-dl-no
#19
Colin Dr Borland, Hervé Guénard
The DL,NO (TL,NO) had its unexpected origins in the Paris "events" of 1968 and the unsuccessful efforts of the UK tobacco industry in the 1970's to create a "safer cigarette". Adoption of the technique has been slow due to the instability of NO in air, lack of standardisation of the technique and lack of agreement as to whether DL,NO is equal to or merely reflects membrane diffusing capacity (DM). With the availability of inexpensive analysers, standardisation of the technique and publication of reference equations we believe that its worldwide use will increase...
December 1, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/27890604/gender-dimorphism-in-pediatric-osa-is-it-for-real
#20
REVIEW
Pablo E Brockmann, Dorit Koren, Leila Kheirandish-Gozal, David Gozal
In epidemiologic studies focused on adults, obstructive sleep apnea (OSA) has higher prevalence in men than in women. The evidence supporting a gender-related discrepant prevalence of OSA is however much more tenuous in children. Here, we aimed to review the evidence concerning gender- based differences in the prevalence of OSA in children, and if so, to examine the evidence with the intent to identify potential factors that may account for this putative association. Gender-based perception and reporting of clinical manifestations of OSA may be modulated by several social and cultural factors in children...
November 23, 2016: Respiratory Physiology & Neurobiology
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