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Reflex influence of carotid baroreceptor inactivation on respiratory resistance in humans  [cached]
Klawe JJ,Tafil-Klawe M,Lewandowski A,Zalewski P
European Journal of Medical Research , 2009, DOI: 10.1186/2047-783x-14-s4-126
Abstract: Our previous study demonstrated that selective carotid baroreceptors activation decreases airway resistance. The aim of the present study was to evaluate the effect of carotid baroreceptor inactivation on the reflex change of respiratory resistance. Twenty healthy men aged between 20 and 25 were included in the study. Selective inactivation of carotid baroreceptors was induced by generating a positive pressure of 40 mmHg for 5 s in two capsules placed bilaterally on the neck over the bifurcation of the carotid arteries. The oscillatory method (Siregnost FD5, Siemens) was used to measure continuously respiratory resistance. Inactivation of carotid baroreceptors produced a short increase in respiratory resistance by 0.39 ± 0.01(SE) mbar/l/s, i.e., 21.7% above the resting level. We conclude that in humans, carotid baroreceptors might have a background contribution to bronchodilator tone. This observation seems to be important for clinical situations of impairment of baroreflex function.
Inhibition of Cardiac Sympathetic Afferent Reflex and Sympathetic Activity by Baroreceptor and Vagal Afferent Inputs in Chronic Heart Failure  [PDF]
Xian-Bing Gan, Yang-Can Duan, Xiao-Qing Xiong, Peng Li, Bai-Ping Cui, Xing-Ya Gao, Guo-Qing Zhu
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0025784
Abstract: Background Cardiac sympathetic afferent reflex (CSAR) contributes to sympathetic activation and angiotensin II (Ang II) in paraventricular nucleus (PVN) augments the CSAR in vagotomized (VT) and baroreceptor denervated (BD) rats with chronic heart failure (CHF). This study was designed to determine whether it is true in intact (INT) rats with CHF and to determine the effects of cardiac and baroreceptor afferents on the CSAR and sympathetic activity in CHF. Methodology/Principal Findings Sham-operated (Sham) or coronary ligation-induced CHF rats were respectively subjected to BD+VT, VT, cardiac sympathetic denervation (CSD) or INT. Under anesthesia, renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded, and the CSAR was evaluated by the RSNA and MAP responses to epicardial application of capsaicin. Either CSAR or the responses of RSNA, MAP and CSAR to Ang II in PVN were enhanced in CHF rats treated with BD+VT, VT or INT. Treatment with VT or BD+VT potentiated the CSAR and the CSAR responses to Ang II in both Sham and CHF rats. Treatment with CSD reversed the capsaicin-induced RSNA and MAP changes and the CSAR responses to Ang II in both Sham and CHF rats, and reduced the RSNA and MAP responses to Ang II only in CHF rats. Conclusions The CSAR and the CSAR responses to Ang II in PVN are enhanced in intact CHF rats. Baroreceptor and vagal afferent activities inhibit CSAR and the CSAR responses to Ang II in intact Sham and CHF rats.
Importance of Assessing the Model Adequacy of Binary Logistic Regression  [PDF]
S.K. Sarkar,Habshah Midi
Journal of Applied Sciences , 2010,
Abstract: Logistic regression is a sophisticated statistical tool for data analysis in both control experimentation and observational studies. The goal of logistic regression is to correctly predict the category of outcome for individual cases using the most parsimonious model. To accomplish this goal, a model is created that includes all predictor variables that are useful in predicting the response variable. The logistic regression model is being used with increasing rate in various fields in data analysis. In spite of such increase, there has been no commensurate increase in the use of commonly available methods for assessing the model adequacy. Failure to address model adequacy may lead to misleading or incorrect inferences. Therefore, the goal of this study is to present an overview of a few easily employed methods for assessing the fit of logistic regression models. The summary measures of goodness-of-fit as Likelihood Ratio Test, Hosmer-Lemeshow goodness-of-fit test, Osius-Rojek large sample approximation test, Stukel test and area under Receiver Operating Characteristic curve indicate that the logistic regression model fits the data quite well. However, recommendations are made for the use of methods for assessing the model adequacy in different aspects before proceed to present the results from a fitted logistic regression model.
Arterial Baroreceptor Reflex Counteracts Long-Term Blood Pressure Increase in the Rat Model of Renovascular Hypertension  [PDF]
Vitaly A. Tsyrlin, Michael M. Galagudza, Nataly V. Kuzmenko, Michael G. Pliss, Nataly S. Rubanova, Yury I. Shcherbin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064788
Abstract: Introduction The present study tested the hypothesis that long-term effects of baroreceptor activation might contribute to the prevention of persistent arterial blood pressure (BP) increase in the rat model of renovascular hypertension (HTN). Methods Repetitive arterial baroreflex (BR) testing was performed in normo- and hypertensive rats. The relationship between initial arterial BR sensitivity and severity of subsequently induced two-kidney one-clip (2K1C) renovascular HTN was studied in Wistar rats. Additionally, the time course of changes in systolic BP (SBP) and cardiac beat-to-beat (RR) interval was studied for 8 weeks after the induction of 2K1C renovascular HTN in the rats with and without sinoaortic denervation (SAD). In a separate experimental series, cervical sympathetic nerve activity (cSNA) was assessed in controls, 2K1C rats, WKY rats, and SHR. Results The inverse correlation between arterial BR sensitivity and BP was observed in the hypertensive rats during repetitive arterial BR testing. The animals with greater initial arterial BR sensitivity developed lower BP values after renal artery clipping than those with lower initial arterial BR sensitivity. BP elevation during the first 8 weeks of renal artery clipping in 2K1C rats was associated with decreased sensitivity of arterial BR. Although SAD itself resulted only in greater BP variability but not in persistent BP rise, the subsequent renal artery clipping invariably resulted in the development of sustained HTN. The time to onset of HTN was found to be shorter in the rats with SAD than in those with intact baroreceptors. cSNA was significantly greater in the 2K1C rats than in controls. Conclusions Arterial BR appears to be an important mechanism of long-term regulation of BP, and is believed to be involved in the prevention of BP rise in the rat model of renovascular HTN.
A METHOD TO ESTIMATE THE OPEN-LOOP GAIN OF ARTERIAL BARORECEPTOR REFLEX IN NORMAL HUMAN SUBJECT
正常人动脉压力感受器反射开环增益的计算方法

魏金河,严拱东,庄祥昌
生物物理学报 , 1986,
Abstract: In order to estimate the open-loop gain (G) of arterial baroreceptor reflex in normal human, three models of arterial blood pressure regulation system with different features were developed, from which the equations for calculating G and the relationship between G and hemodynamic variables were derived. In terms of the equations derived, the open-loop gain of the carotid sinus and aortic baroreceptor reflexes can be estimated, respectively, through properly designed tests. The examples of G calculation were given. In addition, the relative contributions of heart rate and peripheral resistance change to G and the effect of input pressure level on G were also analysed.
Bayesian Inference of Binary Logistic Regression Model for Assessing Erythrocyte Sedimentation Rate  [PDF]
Memet Ali Cengiz,Yuksel Bek,Rezan Yilmaz
Pakistan Journal of Biological Sciences , 2001,
Abstract: Response variables having two possible categories are called binary variables. We often describe two possible categories as the terms of disease and healthy. Binary response data are modelled using the binomial distribution while binary data may be assumed to have the Bernoulli distribution which is a special case of the binomial distribution. This paper investigates logistic regression model to improve the accuracy of predictions and decisions, in the specific context of assessing erythrocyte sedimentation rate. The analysis is enhanced further by adopting a Bayesian approach`
Assessing the effectiveness of the red reflex test (Brückner) in early diagnosis of congenital eye disorders  [cached]
Hamza Yazgan,Ayd?n Y?ld?r?m,Esengül Kele?,Arzu Gebe??i
Turk Pediatri Ar?ivi , 2012,
Abstract: Aim: To evaluate the results of red reflex (Brückner) screenings in newborns and infants.Material and Method: The study included 2718 newborns and infants screened between January 2007 and January 2010. Red reflex examination was done during routine visits at 2-8 weeks of age. In cases where the red reflex was not observed or abnormal red reflex was present, infants were referred to the opthalmology outpatient clinic and risk factors were investigated. The study was approved by the ethics commite (15.01.2007-21).Results: Red reflex examination of 2715 infants (99.8%) were normal. Red reflex was absent in both eyes in two infants (00.7%) and in one eye in one infant (00.2%). The infants with bilateral absence of red reflex were diagnosed with bilateral cataracts, while the infant with unilateral absence of red reflex was diagnosed with retinoblastoma. Risk factor investigation revealed that one of the infants with bilateral cataracts had Down syndrome. No risk factors were identified in the other cases.Conclusions: This study highlights the appropriateness of usage of the red reflex test by pediatricians and primary care physicians during routine examinations of all newborns and infants in order to prevent vision loss and ensure that relevant treatment is successful. (Turk Arch Ped 2012; 47: 165-6)
Assessing Weather Research and Forecasting (WRF) Model Parameterization Schemes Skill to Simulate Extreme Rainfall Events over Dar es Salaam on 21 December 2011  [PDF]
Triphonia Jacob Ngailo, Nyimvua Shaban, Joachim Reuder, Michel D. S. Mesquita, Edwin Rutalebwa, Isaac Mugume, Chiku Sangalungembe
Journal of Geoscience and Environment Protection (GEP) , 2018, DOI: 10.4236/gep.2018.61003
Abstract: This paper evaluates the skills of physical Parameterization schemes in simulating extreme rainfall events over Dar es Salaam Region, Tanzania using the Weather Research and Forecasting (WRF) model. The model skill is determined during the 21 December 2011 flooding event. Ten sensitivity experiments have been conducted using Cumulus, Convective and Planetary boundary layer schemes to find the best combination and optimize the WRF model for the study area for heavy rainfall events. Model simulation results were verified against observed data using standard statistical tests. The model simulations show encouraging and better statistical results with the combination of Kain-Fritsch cumulus parameterization scheme, Lin microphysics scheme and Asymmetric Convection Model 2 (ACM2) planetary boundary scheme than any other combinations of physical parameterization schemes over Dar es Salaam region.
Carotid Baroreceptor Stimulation for the Treatment of Resistant Hypertension  [PDF]
Vasilios Papademetriou,Michael Doumas,Charles Faselis,Constantinos Tsioufis,Stella Douma,Eugene Gkaliagkousi,Chrysanthos Zamboulis
International Journal of Hypertension , 2011, DOI: 10.4061/2011/964394
Abstract: Interventional activation of the carotid baroreflex has been an appealing idea for the management of resistant hypertension for several decades, yet its clinical application remained elusive and a goal for the future. It is only recently that the profound understanding of the complex anatomy and pathophysiology of the circuit, combined with the accumulation of relevant experimental and clinical data both in animals and in humans, has allowed the development of a more effective and well-promising approach. Indeed, current data support a sustained over a transient reduction of blood pressure through the resetting of baroreceptors, and technical deficits have been minimized with a subsequent recession of adverse events. In addition, clinical outcomes from the application of a new implantable device (Rheos) that induces carotid baroreceptor stimulation point towards a safe and effective blood pressure reduction, but longer experience is needed before its integration in the everyday clinical practice. While accumulating evidence indicates that carotid baroreceptor stimulation exerts its benefits beyond blood pressure reduction, further research is necessary to assess the spectrum of beneficial effects and evaluate potential hazards, before the extraction of secure conclusions.
Carotid Baroreceptor Stimulation for the Treatment of Resistant Hypertension  [PDF]
Vasilios Papademetriou,Michael Doumas,Charles Faselis,Constantinos Tsioufis,Stella Douma,Eugene Gkaliagkousi,Chrysanthos Zamboulis
International Journal of Hypertension , 2011, DOI: 10.4061/2011/964394
Abstract: Interventional activation of the carotid baroreflex has been an appealing idea for the management of resistant hypertension for several decades, yet its clinical application remained elusive and a goal for the future. It is only recently that the profound understanding of the complex anatomy and pathophysiology of the circuit, combined with the accumulation of relevant experimental and clinical data both in animals and in humans, has allowed the development of a more effective and well- promising approach. Indeed, current data support a sustained over a transient reduction of blood pressure through the resetting of baroreceptors, and technical deficits have been minimized with a subsequent recession of adverse events. In addition, clinical outcomes from the application of a new implantable device (Rheos) that induces carotid baroreceptor stimulation point towards a safe and effective blood pressure reduction, but longer experience is needed before its integration in the everyday clinical practice. While accumulating evidence indicates that carotid baroreceptor stimulation exerts its benefits beyond blood pressure reduction, further research is necessary to assess the spectrum of beneficial effects and evaluate potential hazards, before the extraction of secure conclusions. 1. Introduction Arterial hypertension represents a major public health problem around the word. Currently, more than one billion people are thought to have hypertension worldwide and the number is estimated to exceed 1.5 billion by 2025 [1]. The advent of antihypertensive therapy has provided drugs that effectively lower blood pressure and contributed significantly to the reduction of cardiovascular events [2]. The rates of awareness, treatment, and control of hypertension have been constantly increased over the last decades; they remain, however, far from optimal [3], underlining the need for the implementation of more effective approaches. Antihypertensive drugs belong to different categories, exerting their actions through different mechanisms that are sometimes complimentary. It has been shown, however, that despite the proper use of several antihypertensive agents, blood pressure remains uncontrolled in a small percentage of hypertensive patients (5%–15%). This subgroup has been called over the years as suffering from refractory, difficult to control, or resistant hypertension (lately). Although the percentage of this subgroup does not seem significant, the actual number of resistant hypertensives is estimated to be very large due to the high prevalence of hypertension in the
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