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Mizuno M, Kawada T, Kamiya A, Miyamoto T, Shimizu S, Shishido T, Smith SA, Sugimachi M. Exercise training augments the dynamic heart rate response to vagal but not sympathetic stimulation in rats. Am J Physiol Regul Integr Comp Physiol 2011; 300:R969-77. [PMID: 21270342 DOI: 10.1152/ajpregu.00768.2010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined the transfer function of autonomic heart rate (HR) control in anesthetized sedentary and exercise-trained (16 wk, treadmill for 1 h, 5 times/wk at 15 m/min and 15-degree grade) rats for comparison to HR variability assessed in the conscious resting state. The transfer function from sympathetic stimulation to HR response was similar between groups (gain, 4.2 ± 1.5 vs. 4.5 ± 1.5 beats·min(-1)·Hz(-1); natural frequency, 0.07 ± 0.01 vs. 0.08 ± 0.01 Hz; damping coefficient, 1.96 ± 0.55 vs. 1.69 ± 0.15; and lag time, 0.7 ± 0.1 vs. 0.6 ± 0.1 s; sedentary vs. exercise trained, respectively, means ± SD). The transfer gain from vagal stimulation to HR response was 6.1 ± 3.0 in the sedentary and 9.7 ± 5.1 beats·min(-1)·Hz(-1) in the exercise-trained group (P = 0.06). The corner frequency (0.11 ± 0.05 vs. 0.17 ± 0.09 Hz) and lag time (0.1 ± 0.1 vs. 0.2 ± 0.1 s) did not differ between groups. When the sympathetic transfer gain was averaged for very-low-frequency and low-frequency bands, no significant group effect was observed. In contrast, when the vagal transfer gain was averaged for very-low-frequency, low-frequency, and high-frequency bands, exercise training produced a significant group effect (P < 0.05 by two-way, repeated-measures ANOVA). These findings suggest that, in the frequency domain, exercise training augments the dynamic HR response to vagal stimulation but not sympathetic stimulation, regardless of the frequency bands.
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Mizuno M, Murphy MN, Mitchell JH, Smith SA. Skeletal muscle reflex-mediated changes in sympathetic nerve activity are abnormal in spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 2011; 300:H968-77. [PMID: 21217062 DOI: 10.1152/ajpheart.01145.2010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In hypertension, the blood pressure response to exercise is exaggerated. We demonstrated previously that this heightened pressor response to physical activity is mediated by an overactive skeletal muscle exercise pressor reflex (EPR), with important contributions from its metaboreflex and mechanoreflex components. However, the mechanisms driving the abnormal blood pressure response to EPR activation are largely unknown. Recent evidence in humans suggests that the muscle metaboreflex partially mediates the enhanced EPR-induced pressor response via abnormally large changes in sympathetic nerve activity (SNA). Whether the muscle mechanoreflex induces similarly exaggerated alterations in SNA in hypertension remains unknown, as does the role of the mechanoreceptors mediating muscle reflex activity. To address these issues, the EPR was selectively activated by electrically inducing hindlimb muscle contraction in decerebrate normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Stimulation of the EPR evoked significantly larger increases in mean arterial pressure (MAP) and renal SNA (RSNA) in SHR compared with WKY (ΔRSNA from baseline: 140 ± 11 vs. 48 ± 8%). The mechanoreflex was stimulated by stretching hindlimb muscle which likewise elicited significantly greater elevations in MAP and RSNA in SHR than WKY (ΔRSNA from baseline: 105 ± 11 vs. 35 ± 7%). Blockade of mechanoreceptors in muscle with gadolinium significantly attenuated the MAP and RSNA responses to contraction and stretch in SHR. These data suggest that 1) the exaggerated pressor response to activation of the EPR and muscle mechanoreflex in hypertension is mediated by abnormally large reflex-induced augmentations in SNA and 2) this accentuated sympathetic responsiveness is evoked, in part, by stimulation of muscle mechanoreceptors.
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Smith SA, Kalcic CL, Safran KA, Stemmer PM, Dantus M, Reid GE. Enhanced characterization of singly protonated phosphopeptide ions by femtosecond laser-induced ionization/dissociation tandem mass spectrometry (fs-LID-MS/MS). JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2010; 21:2031-2040. [PMID: 20888783 DOI: 10.1016/j.jasms.2010.08.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Revised: 08/22/2010] [Accepted: 08/23/2010] [Indexed: 05/29/2023]
Abstract
To develop an improved understanding of the regulatory role that post-translational modifications (PTMs) involving phosphorylation play in the maintenance of normal cellular function, tandem mass spectrometry (MS/MS) strategies coupled with ion activation techniques such as collision-induced dissociation (CID) and electron-transfer dissociation (ETD) are typically employed to identify the presence and site-specific locations of the phosphate moieties within a given phosphoprotein of interest. However, the ability of these techniques to obtain sufficient structural information for unambiguous phosphopeptide identification and characterization is highly dependent on the ion activation method employed and the properties of the precursor ion that is subjected to dissociation. Herein, we describe the application of a recently developed alternative ion activation technique for phosphopeptide analysis, termed femtosecond laser-induced ionization/dissociation (fs-LID). In contrast to CID and ETD, fs-LID is shown to be particularly suited to the analysis of singly protonated phosphopeptide ions, yielding a wide range of product ions including a, b, c, x, y, and z sequence ions, as well as ions that are potentially diagnostic of the positions of phosphorylation (e.g., 'a(n)+1-98'). Importantly, the lack of phosphate moiety losses or phosphate group 'scrambling' provides unambiguous information for sequence identification and phosphorylation site characterization. Therefore, fs-LID-MS/MS can serve as a complementary technique to established methodologies for phosphoproteomic analysis.
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Smith SA. Exercise in hypertension: do skeletal muscle reflexes make this a dangerous proposition? Am J Physiol Heart Circ Physiol 2010; 299:H1302-3. [PMID: 20852038 DOI: 10.1152/ajpheart.00896.2010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Mizuno M, Kawada T, Kamiya A, Miyamoto T, Shimizu S, Shishido T, Smith SA, Sugimachi M. Dynamic characteristics of heart rate control by the autonomic nervous system in rats. Exp Physiol 2010; 95:919-25. [DOI: 10.1113/expphysiol.2010.053090] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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157
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Mizuno M, Murphy MN, Mitchell JH, Smith SA. Sympathetic Nerve Responses to Activation of Chemically-Sensitive Skeletal Muscle Afferent Fibers in Hypertensive Rats. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000384582.17170.0e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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158
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Leal AK, Cherry BH, Murphy MN, Squiers JJ, Mitchell JH, Smith SA. Quantification of the In Vivo Production of Nitric Oxide in the Rat Brainstem. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000385774.08380.7a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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159
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Murphy MN, Squiers JJ, Squiers KE, Smith SA. Skeletal Muscle Reflex Induced Fos Expression within the NTS of Normotensive and Hypertensive Rats. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000384583.55288.a7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mizuno M, Murphy MN, Mitchell JH, Smith SA. The sympathetic response to activation of the skeletal muscle mechanoreflex is enhanced in spontaneously hypertensive rats. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.619.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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161
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Murphy MN, Mizuno M, Smith SA. Skeletal muscle metaboreflex overactivity is partially corrected by decreasing superoxide within the nucleus tractus solitarius of hypertensive rats. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.619.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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162
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Leal AK, Cherry BH, Murphy MN, Squiers JJ, Smith SA. Quantification of the in vivo production of nitric oxide within the nucleus tractus solitarius during activation of the skeletal muscle mechanoreflex. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.807.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Smith SA, Leal AK, Williams MA, Murphy MN, Mitchell JH, Garry MG. The TRPv1 receptor is a mediator of the exercise pressor reflex in rats. J Physiol 2010; 588:1179-89. [PMID: 20142275 DOI: 10.1113/jphysiol.2009.184952] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The skeletal muscle exercise pressor reflex (EPR) induces increases in heart rate (HR) and mean arterial pressure (MAP) during physical activity. This reflex is activated during contraction by stimulation of afferent fibres responsive to mechanical distortion and/or the metabolic by-products of skeletal muscle work. The molecular mechanisms responsible for activating these afferent neurons have yet to be identified. It has been reported that activation of the transient receptor potential vanilloid 1 (TRPv1) receptor within skeletal muscle (localized to unmyelinated afferent fibres) elicits increases in MAP and HR similar to those generated by the EPR. Thus, we hypothesized that stimulation of the TRPv1 receptor during muscle contraction contributes to the activation of the EPR. The EPR was activated by electrically induced static muscle contraction of the hindlimb in decerebrate Sprague-Dawley rats (n = 61) before and after the administration of the TRPv1 receptor antagonists, capsazepine (Capz; 100 microg/100 microl), iodoresinaferatoxin (IRTX; 1 microg/100 microl), or Ruthenium Red (RR; 100 microg/100 microl). Static muscle contraction alone induced increases in both HR (8 +/- 2 bpm) and MAP (21 +/- 3 mmHg). The HR and MAP responses to contraction were significantly lower (P < 0.05) after the administration of Capz (2 +/- 1 bpm; 7 +/- 1 mmHg, respectively), IRTX (3 +/- 2 bpm; 5 +/- 3 mmHg, respectively) and RR (0 +/- 1, bpm; 5 +/- 2 mmHg, respectively). These data suggest that the TRPv1 receptor contributes importantly to activation of the EPR during skeletal muscle contraction in the rat.
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Ozturk A, Smith SA, Gordon-Lipkin EM, Harrison DM, Shiee N, Pham DL, Caffo BS, Calabresi PA, Reich DS. MRI of the corpus callosum in multiple sclerosis: association with disability. Mult Scler 2010; 16:166-77. [PMID: 20142309 PMCID: PMC2820126 DOI: 10.1177/1352458509353649] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Inflammatory demyelination and axon damage in the corpus callosum are prominent features of multiple sclerosis (MS) and may partially account for impaired performance on complex tasks. The objective of this article was to characterize quantitative callosal MRI abnormalities and their association with disability. In 69 participants with MS and 29 healthy volunteers, lesional and extralesional callosal MRI indices were estimated via diffusion tensor tractography. expanded disability status scale (EDSS) and MS functional composite (MSFC) scores were recorded in 53 of the participants with MS. All tested callosal MRI indices were diffusely abnormal in MS. EDSS score was correlated only with age (r = 0.51). Scores on the overall MSFC and its paced serial auditory addition test (PASAT) and 9-hole peg test components were correlated with callosal fractional anisotropy (r = 0.27, 0.35, and 0.31, respectively) and perpendicular diffusivity (r = -0.29, -0.30, and -0.31) but not with overall callosal volume or callosal lesion volume; the PASAT score was more weakly correlated with callosal magnetization-transfer ratio (r = 0.21). Anterior callosal abnormalities were associated with impaired PASAT performance and posterior abnormalities with slow performance on the 9-hole peg test. In conclusion, abnormalities in the corpus callosum can be assessed with quantitative MRI and are associated with cognitive and complex upper-extremity dysfunction in MS.
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165
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Song Q, Xu W, Smith SA, Gao L, Chappell WJ, Cooks RG, Ouyang Z. Ion trap mass analysis at high pressure: an experimental characterization. JOURNAL OF MASS SPECTROMETRY : JMS 2010; 45:26-34. [PMID: 19862776 DOI: 10.1002/jms.1684] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In recent years, it has become increasingly interesting to understand the performance of mass spectrometers at pressures much higher than those employed with conventional operating conditions. This interest has been driven by several influences, including demand for the development of reduced-power miniature mass spectrometers, desire for improved ion transfer into and through mass spectrometers, enhanced-yield preparative mass separations, and mass filtering at the atmospheric pressure interface. In this study, an instrument was configured to allow for the performance characterization of a rectilinear ion trap (RIT) at pressures up to 50 mtorr with air used as the buffer gas. The mass analysis efficiency, mass resolution, isolation efficiency, and collision-induced dissociation (CID) efficiency were evaluated at pressures ranging from 1 to 50 mtorr. The extent of degradation of mass resolution, isolation efficiency and ion stability as functions of pressure were characterized. Also, the optimal resonance ejection conditions were obtained at various pressures. Operations at 50 mtorr demonstrated improved CID efficiency in addition to peak widths of 2 and 5 m/z units (full width at half-maximum, FWHM) for protonated caffeine (m/z 195) and Ultramark (m/z 1521) respectively.
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Berrington de Gonzalez A, Curtis RE, Gilbert E, Berg CD, Smith SA, Stovall M, Ron E. Second solid cancers after radiotherapy for breast cancer in SEER cancer registries. Br J Cancer 2009; 102:220-6. [PMID: 19935795 PMCID: PMC2813734 DOI: 10.1038/sj.bjc.6605435] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Background: Radiotherapy for breast cancer reduces disease recurrence and breast cancer mortality. However, it has also been associated with increased second cancer risks in exposed sites. Methods: We evaluated long-term second cancer risks among 182 057 5-year survivors of locoregional invasive breast cancer diagnosed between 1973 and 2000 and reported to US NCI-SEER Program cancer registries. Multivariate Poisson regression was used to estimate the relative risk (RR) and excess cases of second cancer in women who had surgery and radiotherapy, compared with those who had surgery alone. Second cancer sites were grouped according to doses received from typical tangential breast fields. Results: By the end of 2005 (median follow-up=13.0 years), 15 498 second solid cancers had occurred, including 6491 contralateral breast cancers. The RRs for radiotherapy were 1.45 (95% confidence interval (CI)=1.33–1.58) for high-dose second cancer sites (1+ Gy: lung, oesophagus, pleura, bone and soft tissue) and 1.09 (1.04–1.15) for contralateral breast cancer (≈1 Gy). These risks decreased with increasing age and year of treatment. There was no evidence of elevated risks for sites receiving medium (0.5–0.99 Gy, RR=0.89 (0.74–1.06)) or low doses (<0.5 Gy, RR=1.01 (0.95–1.07)). The estimated excess cases of cancer in women treated with radiotherapy were as follows: 176 (95% CI=69–284) contralateral breast cancers or 5% (2–8%) of the total in all 1+year survivors, and 292 (222–362) other solid cancers or 6% (4–7%) of the total. Conclusions: Most second solid cancers in breast cancer survivors are not related to radiotherapy.
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Xu W, Song Q, Smith SA, Chappell WJ, Ouyang Z. Ion trap mass analysis at high pressure: a theoretical view. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:2144-2153. [PMID: 19682924 DOI: 10.1016/j.jasms.2009.06.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 06/26/2009] [Accepted: 06/29/2009] [Indexed: 05/28/2023]
Abstract
The mass-selective manipulation of ions at elevated pressure, including mass analysis, ion isolation, or excitation, is of great interest for the development of mass spectrometry instrumentation, particularly for systems in which ion traps are employed as mass analyzers or storage devices. While experimental exploration of high-pressure mass analysis is limited by various difficulties, such as ion detection or electrical discharge at high-pressure, theoretical methods have been developed in this work to study ion/neutral collision effects within quadrupole ion traps and to explore their performance at pressures up to 1 Torr. Ion trapping, isolation, excitation, and resonance ejection were investigated over a wide pressure range. The theoretically calculated data were compared with available experimental data for pressures up to 50 mTorr, allowing the prediction of ion trap performance at pressures more than 10 times higher.
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168
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Leal AK, Mitchell JH, Smith SA. Alterations In Central-acting Nitric Oxide Contribute To The Abnormal Skeletal Muscle Metaboreflex In Hypertension. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000353356.73170.65] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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169
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Hawkins MN, Leal AK, Mitchell JH, Smith SA. Decreasing Superoxide Within The Nucleus Tractus Solitarius Partially Corrects Skeletal Muscle Mechanoreflex Overactivity In Hypertension. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000355557.36753.9e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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170
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Nash RE, Loehr JA, Lee SM, English KL, Evans H, Smith SA, Hagan RD. Changes In Muscle Volume And Strength Following 16 Weeks Of Training Using The Advanced Resistive Exercise Device (ARED) And Free Weights. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000355419.43318.aa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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171
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Fico M, Maas JD, Smith SA, Costa AB, Ouyang Z, Chappell WJ, Cooks RG. Circular arrays of polymer-based miniature rectilinear ion traps. Analyst 2009; 134:1338-47. [PMID: 19562199 DOI: 10.1039/b822140e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The design and operation of an annular array of parallel, miniature rectilinear ion traps (RITs) is discussed. Stereolithography apparatus (SLA), a previously validated method for ion trap fabrication, was applied here to construct an array of mass analyzers and their mounting hardware. Two versions of the array were tested, using either six or twelve stretched RITs (x0 = 1.66 mm, y0 = 1.33 mm, z = 16.66 mm) mounted in parallel about the circumference of a circle with the interior and exterior x-electrode planes oriented tangential to the inner and outer annulus rings, respectively. The arrangement of the ion traps is such that the ions are radially ejected just above the throat of a centrally located electron multiplier detector into which they are accelerated. The mass analyzer array was mounted in a custom vacuum manifold. The resolution, mass-to-charge ratio (m/z) range, and MS/MS capabilities were tested using electrospray ionization (ESI). The devices were tested in two configurations: (i) separate ion sources for each trap, and (ii) a single ion source for the entire array.
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Leal AK, Mitchell JH, Smith SA. Exaggerations in skeletal muscle metaboreflex activity are attenuated by increasing nitric oxide production within the brainstem of spontaneously hypertensive rats. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.608.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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173
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Hawkins MN, Squiers J, Leal AK, Mitchell JH, Smith SA. Neuronal nitric oxide synthase (nNOS) and c‐Fos expression in the nucleus tractus solitarius (NTS) of normotensive and hypertensive rats. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.608.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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174
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Jordan AS, White DP, Lo YL, Wellman A, Eckert DJ, Yim-Yeh S, Eikermann M, Smith SA, Stevenson KE, Malhotra A. Airway dilator muscle activity and lung volume during stable breathing in obstructive sleep apnea. Sleep 2009; 32:361-8. [PMID: 19294956 PMCID: PMC2647790 DOI: 10.1093/sleep/32.3.361] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
STUDY OBJECTIVES Many patients with obstructive sleep apnea (OSA) have spontaneous periods of stable flow limited breathing during sleep without respiratory events or arousals. In addition, OSA is often more severe during REM than NREM and more severe during stage 2 than slow wave sleep (SWS). The physiological mechanisms for these observations are unknown. Thus we aimed to determine whether the activity of two upper airway dilator muscles (genioglossus and tensor palatini) or end-expiratory lung volume (EELV) differ between (1) spontaneously occurring stable and cyclical breathing and (2) different sleep stages in OSA. DESIGN Physiologic observation. SETTING Sleep physiology laboratory. STUDY PARTICIPANTS 15 OSA patients with documented periods of spontaneous stable breathing. INTERVENTION Subjects were instrumented with intramuscular electrodes for genioglossus and tensor palatini electromyograms (EMG(GG) and EMG(TP)), chest and abdominal magnetometers (EELV measurement), an epiglottic pressure catheter (respiratory effort), and a mask and pneumotachograph (airflow/ventilation). Patients slept supine overnight without CPAP. MEASUREMENTS AND RESULTS Peak and Tonic EMG(GG) were significantly lower during cyclical (85.4 +/- 2.7 and 94.6 +/- 4.7 % total activity) than stable breathing (109.4 +/- 0.4 and 103 +/- 0.8% total activity, respectively). During respiratory events in REM, tonic EMG(GG) activity was lower than during respiratory events in stage 2 (71.9 +/- 5.1 and 119.6 +/- 5.6% total activity). EMG(GG) did not differ between stable stage 2 and stable SWS (98.9 +/- 3.2 versus 109.7 +/- 4.4% total activity), nor did EMG(TP) or EELV differ in any breathing condition/sleep stage. CONCLUSIONS Increased genioglossus muscle tone is associated with spontaneous periods of stable flow limited breathing in the OSA subjects studied. Reductions in genioglossus activity during REM may explain the higher severity of OSA in that stage. Increased lung volume and tensor palatini activity do not appear to be major mechanisms enabling spontaneous stable flow limited breathing periods.
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Song Q, Smith SA, Gao L, Xu W, Volný M, Ouyang Z, Cooks RG. Mass Selection of Ions from Beams Using Waveform Isolation in Radiofrequency Quadrupoles. Anal Chem 2009; 81:1833-40. [PMID: 19178148 DOI: 10.1021/ac802213p] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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