Sympathetic activity is not increased in L-NAME hypertensive rats

Santos FM, Dias DPM, Silva CAA, Fazan Jr R, Salgado HC. Sympathetic activity is not increased in L-NAME hypertensive rats. Am J Physiol Regul Integr Comp Physiol 298: R89-R95, 2010. First published November 4, 2009; doi:10.1152/ajpregu.00449.2009.-The role played by the sympathetic drive in the development of N(G)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension is not firmly established. Therefore, the present study was undertaken in conscious rats in which hypertension was induced by treatment with L-NAME over the course of either 2 or 14 days. Mean arterial pressure (MAP) was measured via a catheter placed in the femoral artery, drugs were administered via a cannula placed in the femoral vein, and renal sympathetic nerve activity (RSNA) was monitored using an implanted electrode. Despite the remarkable increase in arterial pressure, heart rate did not change after treatment with L-NAME. RSNA was similar in L-NAME-induced hypertensive rats treated over the course of 2 or 14 days, as well as in normotensive rats. It was also demonstrated that L-NAME-induced hypertensive rats displayed a resetting of the baroreflex control of RSNA to hypertensive levels, with decreased sensitivity over the course of 2 or 14 days. Furthermore, the sympathetic-vagal balance examined in the time and frequency domain and the renal and plasma norepinephrine content did not differ between groups. In conclusion, the evaluation of the sympathetic drive in conscious rats demonstrated that the arterial hypertension induced by L-NAME treatment over the course of 2 and 14 days does not show sympathetic overactivity.

Are l-glutamate and ATP cotransmitters of the peripheral chemoreflex in the rat nucleus tractus solitarius ?

Peripheral chemoreflex activation in awake rats or in the working heart-brainstem preparation (WHBP) produces sympathoexcitation, bradycardia and an increase in the frequency of phrenic nerve activity. Our focus is the neurotransmission of the sympathoexcitatory component of the chemoreflex within the nucleus of the tractus solitarius (NTS), and recently we verified that the simultaneous antagonism of ionotropic glutamate and purinergic P(2) receptors in the NTS blocked the pressor response and increased thoracic sympathetic activity in awake rats and WHBP, respectively, in response to peripheral chemoreflex activation. These previous data suggested the involvement of ATP and L-glutamate in the NTS in the processing of the sympathoexcitatory component of the chemoreflex by unknown mechanisms. For a better understanding of these mechanisms, here we used a patch-clamp approach in brainstem slices to evaluate the characteristics of the synaptic transmission of NTS neurons sending projections to the ventral medulla, which include the premotor neurons involved in the generation of the sympathetic outflow. The NTS neurons sending projections to the ventral medulla were identified by previous microinjection of the membrane tracer dye, 1,1`-dioctadecyl-3,3,3`,3`-tetramethylindocarbocyanine perchlorate (DiI), in the ventral medulla and the spontaneous (sEPSCs) and tractus solitarius (TS)-evoked excitatory postsynaptic current (TS-eEPSCs) were recorded using patch clamp. With this approach, we made the following observations on NTS neurons projecting to the ventral medulla: (i) the sEPSCs and TS-eEPSCs of DiI-labelled NTS neurons were completely abolished by 6,7-dinitroquinoxaline-2,3(1H,4H)-dione (DNQX), an antagonist of ionotropic non-NMDA glutamatergic receptors, showing that they are mediated by L-glutamate; (ii) application of ATP increased the frequency of appearance of spontaneous glutamatergic currents, reflecting an increased exocytosis of glutamatergic vesicles; and (iii) ATP decreased the peak of TS-evoked glutamatergic currents. We conclude that L-glutamate is the main neurotransmitter of spontaneous and TS-evoked synaptic activities in the NTS neurons projecting to the ventral medulla and that ATP has a dual modulatory role on this excitatory transmission, facilitating the spontaneous glutamatergic transmission and inhibiting the TS-evoked glutamatergic transmission. These data also suggest that ATP is not acting as a cotransmitter with L-glutamate, at least at the level of this subpopulation of NTS neurons studied.

Increased cardiac sympathetic drive and reduced vagal modulation following endothelin receptor antagonism in healthy conscious rats

1. The present study evaluated changes in autonomic control of the cardiovascular system in conscious rats following blockade of endothelin (ET) receptors with bosentan. 2. Rats were treated with bosentan or vehicle (5% gum arabic) for 7 days by gavage. 3. Baseline heart rate (HR) was higher in the bosentan-treated group compared with the control group (418 +/- 5 vs 357 +/- 4 b.p.m., respectively; P < 0.001). This baseline tachycardia was associated with a lower baroreflex sensitivity of the bradycardiac and tachycardiac responses in the bosentan-treated group compared with the control group. Sequential blockade of the parasympathetic and sympathetic autonomic nervous system with methylatropine and propranolol showed a higher intrinsic HR in the bosentan-treated group compared with the control group (411 +/- 5 vs 381 +/- 4 b.p.m., respectively; P < 0.05). This was accompanied by a higher cardiac sympathetic tone (31 +/- 1 vs 13 +/- 1%, respectively; P < 0.01) and a lower vagal parasympathetic tone (69 +/- 2 vs 87 +/- 2%, respectively; P < 0.01) in the bosentan-treated group compared with the control group. Variance and high-frequency oscillations of pulse interval (PI) variability in absolute and normalized units were lower in the bosentan-treated group than in the control group. Conversely, low-frequency (LF) oscillations of PI variability in absolute and normalized units, as well as variance and LF oscillations of systolic arterial pressure variability, were greater in the bosentan-treated group than the control group. 4. Overall, the data indicate an increased cardiac sympathetic drive, as well as lower vagal parasympathetic activity and baroreflex sensitivity, in conscious rats after chronic blockade of ET receptors with bosentan.

Efficacy of cidofovir in recurrent juvenile respiratory papillomatosis

The efficacy of cidofovir in juvenile recurrent respiratory papillomatosis (JRRP) remains uncertain due to the lack of published case-control studies. Aim: To establish factors affecting the progression of JRRP prognosis, and to evaluate cidofovir for eradicating JRRP. Study Design: Retrospective. Methods: 22 children with JRRP were evaluated at a referral center. All children underwent surgical debulking, followed by cidofovir injection (Group 2) or not (Group 1). Age at diagnosis was correlated with the Derkay score and disease outcome. Disease progression was compared between groups 1 and 2. Results: fifteen children were considered disease-free; 8 were in Group 2 and 7 in Group 1. Age and total and clinical scores (P<0.05) were negatively correlated. The mean number of surgeries required to control the disease was identical in both groups; the duration of treatment until remission was significantly higher in Group 1 (P<0,05). Conclusion: JRRP is more aggressive in earlier onset disease. The duration of treatment was significantly lower in patients treated with cidofovir until eradication of JRRP compared to patients treated with surgery only.

Cigarette smoke exposure impairs respiratory epithelial ciliogenesis

Background: Cigarette smoke exposure is considered an important negative prognostic factor for chronic rhinosinusitis (CRS) patients. However, there is no clear mechanistic evidence implicating cigarette smoke exposure in the poor clinical evolution of the disease or in the maintenance of the inflammatory state characterizing CRS. This study aimed to evaluate the effects of cigarette smoke exposure on respiratory cilia differentiation. Methods: Monse nasal septal epithelium cultures grown at an air-liquid interface were used as a model of respiratory epithelium. After 5 days of cell growth, cultures were exposed to air on the apical surface. Additionally, cigarette smoke condensate (CSC; the particulate phase of tobacco smoke) or cigarette smoke extract (CSE; the volatile phase) Were diluted in the basolateral compartment in different concentrations. After 15 days of continuous exposure, scanning electron microscopy and immunofluorescence for type IV tubulin were used to determine presence and maturation of cilia. Transepithelial resistance was also recorded to evaluate confluence and physiological barrier integrity. Results: CSC and CSE impair ciliogenesis in a dose-dependent manner with notable effects in concentrations higher than 30 mu g/mL, yielding >70% nonciliation and shorter cilia compared With control. No statistical difference on transepithelial resistance was evident. Conclusion: CSC and CSE exposure negatively impacts ciliogenesis of respiratory cells at concentrations not effecting transepithelial resistance. The impairment on ciliogenesis reduce the mucociliary clearance apparatuts after injury and/or infection and may explain the poor response to therapy for CRS patients exposed to tobacco smoke.

Respiratory effects of tobacco smoking among young adults

Background. Respiratory symptoms associated with smoking habit seem to be age dependent. However, there are few reports about the effect of tobacco in young populations. The objective of this study was to analyze the effect of smoking on respiratory symptoms and lung function in 23- to 25-year-old adults in Brazil. This study had a cross-sectional design and included 2063 young people in the city of Ribeirao Preto, Sao Paulo State. Methods: Subjects completed a questionnaire used by the European Community Respiratory Health Survey and underwent spirometry and bronchial challenge test with methacholine. Multiple logistic regression analysis and multiple linear regression analysis were carried out to assess the association between smoking and respiratory symptoms, bronchial hyperresponsiveness, forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC), adjusted for confounding variables. Results: Prevalence of smoking habit was 17.2% with consumption (median) of 10 cigarettes per day (interquartile range 3-20). There was a significant association between smoking and respiratory symptoms. Smoking was associated to wheezing with odds ratio (95%Cl) of 6.11 (4.03-9.28) among those smoking :10 cigarettes per day and 3.36 (2.11-5.37) among those smoking <10 cigarettes per day. Associations were found for other respiratory symptoms. Smoking was associated with lower FEV1/FVC ratio. No association was detected between smoking and FEV1 or bronchial hyperresponsiveness. Conclusions: These findings highlight the early health consequences of smoking among young adults. These results prompt the necessity to elaborate urgent programs to reduce tobacco habit in young populations.

Influence of aging, tidal volume, and respiratory rate on Doppler echocardiographic indices of diastolic function in normal male subjects: A quantitative evaluation

Background: Although the influence of respiration on ventricular filling, as evaluated by Doppler technique, and the evaluation of diastolic velocities of mitral valve annulus (MVA), as measured by Doppler tissue imaging (DTI), can provide valuable information for the study of left ventricular (LV) diastolic function, the concomitant effects of aging, tidal volume (TV), and respiratory rate (RR) on these velocities have not been quantitatively investigated. Methods: We evaluated 12 normal male volunteers (Group I) aged 20-26 years (mean: 22.8) and 8 normal subjects aged 41 to 54 years old (mean: 45.9) (Group II). Using DTI we measured peak early (E-a) and late (A(a)) velocities of longitudinal axis expansion at lateral and medial MVA. Doppler mitral and tricuspid flow velocities were measured: peak early (E) and late (A) inflow velocity, early (E-i) and late (A(i)) flow integral, and deceleration time of peak early mitral flow velocity (DT). Respiratory cycles were simultaneously recorded at RR of 9, 12, 15, and 18 cycles/min and TV of 600 and 900 mL during respiration (RESP). Results and conclusions: (1) E, A, and A(i) in MV had negligible change during respiration, but E-i was significantly reduced during inspiration; (2) DT reduced slightly with inspiration, but the change was significant only with TV of 900 mL; (3) an important increase of E in right ventricular flow was observed during inspiration; (4) variations of RR and TV did not significantly influence right and left ventricular inflow in normal subjects, in the conditions of this investigation; (5) a significant increase of E-a at medial MVA was documented during inspiration only in young subjects; (6) a significant decrease of A(a) at medial MVA was observed during inspiration in both groups of volunteers; (7) RR and TV did not influence MVA velocities in young and adult subjects; (8) a consistent reduction in E-a and a significant increase in A(a) were observed with increasing age; (9) these changes were more conspicuous and consistent than those documented in ventricular filling when young and middle-age men are compared, suggesting that the DTI is more sensitive to detect changes in diastolic function; and (10) in addition, these data suggest that, for evaluation of diastolic function, in clinical context, it is not necessary to control rigorously RR or TV.

Asymmetrical changes in lumbar sympathetic nerve activity following stimulation of the sciatic nerve in rat

Noxious stimulation of the leg increases hind limb blood flow (HBF) to the ipsilateral side and decreases to the contralateral in rat. Whether or not this asymmetrical response is due to direct control by sympathetic terminals or mediated by other factors such as local metabolism and hormones remains unclear. The aim of this study was to compare responses in lumbar sympathetic nerve activity, evoked by stimulation of the ipsilateral and contralateral sciatic nerve (SN). We also sought to determine the supraspinal mechanisms involved in the observed responses. In anesthetized and paralyzed rats, intermittent electrical stimulation (1 mA, 0.5 Hz) of the contralateral SN evoked a biphasic sympathoexcitation. Following ipsilateral SN stimulation, the response is preceded by an inhibitory potential with a latency of 50 ms (N=26). Both excitatory and inhibitory potentials are abolished following cervical Cl spinal transection (N=6) or bilateral microinjections of muscimol (N=6) in the rostral ventrolateral medulla (RVLM). This evidence is suggestive that both sympathetic potentials are supraspinally mediated in this nucleus. Blockade of RVLM glutamate receptors by microinjection of kynurenic acid (N=4) selectively abolished the excitatory potential elicited by ipsilateral SN stimulation. This study supports the physiological model that activation of hind limb nociceptors evokes a generalized sympathoexcitation, with the exception of the ipsilateral side where there is a withdrawal of sympathetic tone resulting in an increase in HBF. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.

Effects of progressive exercise during phase I cardiac rehabilitation on the heart rate variability of patients with acute myocardial infarction

Purpose. aEuro integral Heart rate variability (HRV) decreases after an acute myocardial infarction (AMI) due to changes in cardiac autonomic balance. The purpose of the present study, therefore, was to evaluate the effects of a progressive exercise protocol used in phase I cardiac rehabilitation on the HRV of patients with post-AMI. Material and methods. aEuro integral Thirty-seven patients who had been admitted to hospital with their first non-complicated AMI were studied. The treated group (TG, n == 21, age == 52 +/-+/- 12 years) performed a 5-day programme of progressive exercise during phase I cardiac rehabilitation, while the control group (CG, n == 16, age == 54 +/-+/- 11 years) performed only respiratory exercises. Instantaneous heart rate (HR) and RR interval were acquired by a HR monitor (Polar (R) A (R) S810i). HRV was analysed by frequency domain methods. Power spectral density was expressed as normalised units (nu) at low (LF) and high (HF) frequencies, and as LF/HF. Results. aEuro integral After 5 days of progressive exercise, the TG showed an increase in HFnu (35.9 +/-+/- 19.5 to 65.19 +/-+/- 25.4) and a decrease in LFnu and LF/HF (58.9 +/-+/- 21.4 to 32.5 +/-+/- 24.1; 3.12 +/-+/- 4.0 to 1.0 +/-+/- 1.5, respectively) in the resting position (p < 0.05). No changes were observed in the CG. Conclusions. aEuro integral A progressive physiotherapeutic exercise programme carried out during phase I cardiac rehabilitation, as supplement to clinical treatment increased vagal and decreased sympathetic cardiac modulation in patients with post-AMI.

Impact of implementing an exclusively dedicated respiratory isolation room in a Brazilian tertiary emergency department

Background Occupational risk due to airborne disease challenges healthcare institutions. Environmental measures are effective but their cost-effectiveness is still debatable and most of the capacity planning is based on occupational rates. Better indices to plan and evaluate capacity are needed. Goal To evaluate the impact of installing an exclusively dedicated respiratory isolation room (EDRIR) in a tertiary emergency department (ED) determined by a time-to-reach-facility method. Methods A group of patients in need of respiratory isolation were first identified-group I (2004; 29 patients; 44.1 +/- 3.4 years) and the occupational rate and time intervals (arrival to diagnosis, diagnosis to respiratory isolation indication and indication to effective isolation) were determined and it was estimated that adding an EDRIR would have a significant impact over the time to isolation. After implementing the EDRIR, a second group of patients was gathered in the same period of the year-group II (2007; 50 patients; 43.4 +/- 1.8 years) and demographic and functional parameters were recorded to evaluate time to isolation. Cox proportional hazard models adjusted for age, gender and inhospital respiratory isolation room availability were obtained. Results Implementing an EDRIR decreased the time from arrival to indication of respiratory isolation (27.5 +/- 9.3 X 3.7 +/- 2.0; p = 0.0180) and from indication to effective respiratory isolation (13.3 +/- 3.0 X 2.94 +/- 1.06; p = 0.003) but not the respiratory isolation duration and total hospital stay. The impact on crude isolation rates was very significant (8.9 X 75.4/100.000 patients; p < 0.001). The HR for effective respiratory isolation was 26.8 (95% CI 7.42 to 96.9) p < 0.001 greater for 2007. Conclusion Implementing an EDRIR in a tertiary ED significantly reduced the time to respiratory isolation.

Lower respiratory tract infections among human immunodeficiency virus-exposed, uninfected infants

Objectives: To evaluate whether maternal HIV disease severity during pregnancy is associated with an increased likelihood of lower respiratory tract infections (LRTIs) in HIV-exposed, uninfected infants. Methods: HIV-exposed, uninfected, singleton, term infants enrolled in the NISDI Perinatal Study, with birth weight >2500 g were followed from birth until 6 months of age. LRTI diagnoses, hospitalizations, and associated factors were assessed. Results: Of 547 infants, 103 (18.8%) experienced 116 episodes of LRTI (incidence = 0.84 LRTIs/100 child-weeks). Most (81%) episodes were bronchiolitis. Forty-nine (9.0%) infants were hospitalized at least once with an LRTI. There were 53 hospitalizations (45.7%) for 116 LRTI episodes. None of these infants were breastfed. The odds of LRTI in infants whose mothers had CD4% <14 at enrollment were 4.4 times those of infants whose mothers had CD4% >= 29 (p = 0.003). The odds of LRTI in infants with a CD4+ count (cells/ mm(3)) <750 at hospital discharge were 16.0 times those of infants with CD4+ >= 750 (p = 0.002). Maternal CD4+ decline and infant hemoglobin at the 6-12 week visit were associated with infant LRTIs after 6-12 weeks and before 6 months of age. Conclusions: Acute bronchiolitis is common and frequently severe among HIV-exposed, uninfected infants aged 6 months or less. Lower maternal and infant CD4+ values were associated with a higher risk of infant LRTIs. Further understanding of the immunological mechanisms of severe LRTIs is needed. (C) 2010 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Evaluation of DNA damage by the alkaline comet assay of the olfactory and respiratory epithelia of dogs from the city of Sao Paulo, Brazil

Animals kept as pets may be considered sentinels for environmental factors to which humans could be exposed. Olfactory and respiratory epithelia are directly subjected to airborne factors, which could cause DNA lesions, and the alkaline comet assay is considered a reliable tool for the assessment of DNA damage. The objective of this work is to evaluate the extent of DNA damage by the comet assay of the olfactory and respiratory epithelia of dogs from different regions of the city of sao Paulo, Brazil. Thirty-three clinically healthy dogs, aged 5 years or more, were used in the study, with 7 from the North region of Sao Paulo, 7 from the South region, 3 dogs from the East region, and 16 dogs from the West city region. Three dogs younger than 6 months were used as controls. DNA damage was analyzed by the alkaline comet assay. We observed no difference in histopathological analysis of olfactory and respiratory epithelia between dogs from different regions of Sao Paulo. Dogs older than 5 years presented significantly higher comet length in both olfactory and respiratory epithelia, when compared with controls, indicating DNA damage. When separated by regions, olfactory and respiratory epithelia presented similar DNA damage in dogs from different regions of Sao Paulo, corroborating with similar levels of particulate matter index (PM10) in all regions of the city. In this study, we report for the first time that the comet assay can be used to quantify the extent of DNA damage in dog olfactory and respiratory epithelia, and that comet length (DNA damage) increases with age, probably due to environmental factors. Air pollution, as measured by PM 10, can be responsible for this DNA damage. (C) 2009 Elsevier GmbH. All rights reserved.

Coupling of composite resin cements to quartz fiber posts: A comparison of industrial and ""chairside"" treatments of the post surface

Purpose: To evaluate the influence of surface treatments on microtensile bond strength of luting resin cements to fiber posts. Materials and Methods: Forty-two quartz fiber posts (Light Post, RTD) were divided into 7 groups (n = 6) according to the surface treatment. I and 11: experimental patented industrial treatment consisting of zirconium oxide coating and silanization (RTD); III: industrial treatment followed by adhesive application (XPBond, Dentsply Caulk); IV: adhesive (XPBond); V: adhesive (Prime&Bond NT, Dentsply Caulk); VI: silane (Calibra Silane, Dentsply Caulk); VII: no treatment. Adhesives were used in the self-curing mode. Two cements (Sealbond, RTD - group 1, and Calibra, Dentsply Caulk - groups 11 to VII) were applied on the posts to produce cylindrical specimens. Post/cement interfaces were evaluated under SEM. The surface of the industrially coated posts was examined using energy dispersive analysis by x-ray. Cylinders were cut to obtain microtensile sticks that were loaded in tension at a crosshead speed of 0.5 mm/min until failure. Statistical analysis was performed using Kruskal-Wallis analysis of variance followed by Dunn`s multiple range test for post-hoc comparisons (p < 0.05). Weibull analysis was also performed. Results: The post/cement bond strength was significantly higher on fiber posts treated industrially (I: 23.14 +/- 8.05 MPa; II: 21.56 +/- 7.07 MPa; III: 22.37 +/- 7.00 MPa) or treated with XPBond adhesive (IV: 21.03 +/- 5.34 MPa) when compared to Prime&Bond NT application (V: 14.05 +/- 5.06 MPa), silanization (VI: 6.31 +/- 4.60 MPa) or no treatment (VII: 4.62 +/- 4.31) of conventional fiber posts (p < 0.001). Conclusion: The experimental industrial surface treatment and the adhesive application enhanced fiber post to resin cement interfacial strength. Industrial pretreatment may simplify the clinical luting procedure.

Cervical mobilisation: concurrent effects on pain, sympathetic nervous system activity and motor activity

Recent findings that spinal manual therapy (SMT) produces concurrent hypoalgesic and sympathoexcitatory effects have led to the proposal that SMT may exert its initial effects by activating descending inhibitory pathways from the dorsal periaqueductal gray area of the midbrain (dPAG). In addition to hypoalgesic and sympathoexcitatory effects, stimulation of the dPAG in animals has been shown to hal e a facilitatory effect on motor activity. This study sought to further investigate the proposal regarding SMT and the FAG by including a test of motor function in addition to the variables previously investigated, Using a condition randomised, placebo-controlled, double blind, repeated measures design, 30 subjects with mid to lon er cervical spine pain of insidious onset participated in the study. The results indicated that the cervical mobilisation technique produced a hypoalgesic effect as revealed by increased pressure pain thresholds on the side of treatment (P = 0.0001) and decreased resting visual analogue scale scores (P = 0.049). The treatment technique also produced a sympathoexcitatory effect with an increase in skin conductance (P < 0.002) and a decrease in skin temperature (P = < 0.02). There was a decrease in superficial neck flexor muscle activity (P < 0.0002) at the lower levels of a staged cranio-cervical flexion test. This could imply facilitation of the deep neck flexor muscles with a decreased need for co-activation of the superficial neck flexors, The combination of all findings,would support the proposal that SMT may, at least initially, exert part of its influence via activation of the PAG, (C) 2000 Harcourt Publishers Ltd.