Developmental nicotine exposure (DNE) is associated with increased risk of cardiorespiratory, intellectual, and behavioral abnormalities in neonates, and is a risk factor for apnea of prematurity, altered arousal responses and Sudden Infant Death Syndrome. Alterations in nicotinic acetylcholine receptor signaling (nAChRs) after DNE lead to changes in excitatory neurotransmission in neural networks that control breathing, including a heightened excitatory response to AMPA microinjection into the hypoglossal motor nucleus. Here, we report on experiments designed to probe possible postsynaptic and presynaptic mechanisms that may underlie this plasticity. Pregnant dams were exposed to nicotine or saline via an osmotic mini-pump implanted on the 5th day of gestation. We used whole-cell patch clamp electrophysiology to record from hypoglossal motoneurons (XIIMNs) in thick medullary slices from neonatal rat pups (N = 26 control and 24 DNE cells). To enable the translation of our findings to breathing-related consequences of DNE, we only studied XIIMNs that were receiving rhythmic excitatory drive from the respiratory central pattern generator. Tetrodotoxin was used to isolate XIIMNs from presynaptic input, and their postsynaptic responses to bath application of L-glutamic acid (glutamate) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) were studied under voltage clamp. DNE had no influence on inward current magnitude evoked by either glutamate or AMPA. However, in cells from DNE animals, bath application of AMPA was associated with a right shift in the amplitude distribution (P = 0.0004), but no change in the inter-event interval distribution of miniature excitatory postsynaptic currents (mEPSCs). DNE had no influence on mEPSC amplitude or frequency evoked by glutamate application, or under (unstimulated) baseline conditions. Thus, in the presence of AMPA, DNE is associated with a small but significant increase in quantal size, but no change in the probability of glutamate release.

The physiological responses to upper-body exercise (UBE) are well established. Few published studies, however, have attempted to elucidate the mechanical ventilatory responses to UBE. There is empirical evidence that respiratory function may be compromised by UBE during which the ventilatory and postural functions of the ‘respiratory’ muscles may be exacerbated. Therefore, the aims of this thesis were: 1) to characterise the mechanical-ventilatory responses to UBE in healthy subjects; 2) to explore the putative mechanisms that underpin the respiratory responses to UBE; and 3) to assess whether the mechanical-ventilatory stress imposed by UBE induces contractile fatigue of the respiratory muscles. Compared to lower-body exercise (LBE; leg cycling) at ventilation-matched work rates, UBE (arm-cranking) resulted in constraint of tidal volume, higher respiratory frequency, and greater neural drive to the respiratory muscles. Furthermore, end-expiratory lung volume was significantly elevated during peak UBE compared to LBE (39 ± 8 vs. 29 ± 8% vital capacity, p < 0.05) and was independent of expiratory flow limitation. In assessing the influence of cadence on cardiorespiratory function and respiratory mechanics, submaximal arm-cranking at high cadence (90 rev.min-1) induced significantly greater cardiorespiratory stress, a trend towards elevated intra-thoracic pressures and significantly greater perceptions of dyspnoea than at low cadence (50 rev.min-1). Furthermore, there was a greater prevalence of locomotor-respiratory coupling at high cadences (p < 0.05), suggestive of greater antagonistic loading of the thoracic muscles, likely the result of static postural contractions. Finally, there was objective evidence of abdominal muscle contractile fatigue in response to severe- but not heavy-intensity UBE. Specifically, there was a 22% decrease in gastric twitch pressure from pre- to post-exercise in response to magnetic stimulation of the thoracic nerves (p < 0.05). However, there was limited evidence of exercise-induced diaphragm fatigue, as assessed using magnetic stimulation of the phrenic nerves (p > 0.05). In conclusion, mechanical-ventilatory function may be compromised during UBE due to complex interactions between thoracic muscle recruitment, central neural drive and thoracic volume displacement. This thesis presents novel findings which may have important functional implications for clinical populations who report breathlessness during activities of daily living that involve the upper-body, as well as for athletes engaged in upper-body sports.

Thesis advisor: Patricia A. Tabloski / This randomized pilot intervention study examined the influence of two self regulatory techniques, coherent breathing and meditation, in reducing perceived stress and anxiety scores, and increasing holistic wellness scores in college freshmen and sophomores. Too much stress is well documented throughout the literature to have adverse effects on physical, mental and spiritual health. Stress has been identified by college students as a barrier to academic performance. Both coherent breathing and meditation inhibit the secretion of stress hormone production responsible for the persistent state of sympathetic dominance experienced with daily living. A total sample of 37 Boston College freshmen and 3 sophomores was recruited for random assignment into three groups, meditation, n=14, coherent breathing n=14, and reading group as a control, n=12. The instruction of the intervention techniques was conducted through an 8 hour weekend workshop on two dates, October 2010, and September 2011. Participants were asked to practice their respective techniques daily for three weeks. All groups met once weekly throughout the duration of the study. Univariate ANOVA was conducted on pre and post test change of scores for the following instruments: Cohen's Perceived Stress Scale(PSS), Speilberger's State-Trait Anxiety Index, (STAI), and the Mind Body Spirit Wellness Behavior Characteristic Index (MBS-WBCI). The two self regulatory stress management techniques of coherent breathing and meditation demonstrated positive effects for this self selected small sample of freshmen and sophomores at Boston College. Participants of both intervention groups experienced reductions in perceived stress, state and trait anxiety scores, as well as increases in holistic wellness scores, as compared with controls. The favorable results achieved from this study strongly support future research investigations with larger samples and expanded populations. The implementation of mandatory college life skills courses incorporating these techniques could advance the potential for evaluating these techniques in a true randomized sample. The college environment provides an ideal opportunity for introducing prevention and early intervention techniques addressing mental health issues for students in their formative years. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Connell School of Nursing. / Discipline: Nursing.

Mathematics, physics, biology, and computer science are combined to create computational modeling, which studies the behaviors and reactions of complex biomedical problems. Modern biomedical research relies significantly on realistic computational human models or “virtual humans�. Relevant study areas utilizing computational human models include electromagnetics, solid mechanics, fluid dynamics, optics, ultrasound propagation, thermal propagation, and automotive safety research. These and other applications provide ample justification for the realization of the Visible Human Project® (VHP)-Female v. 4.0, a new platform-independent full body electromagnetic computational model. Along with the VHP-Female v. 4.0, a realistic and anatomically justified Dynamic Breathing Sequence is developed. The creation of such model is essential to the development of biomedical devices and procedures that are affected by the dynamics of human breathing, such as Magnetic Resonance Imaging and the calculation of Specific Absorption Rate. The model can be used in numerous application, including Breath-Detection Radar for human search and rescue.

Biological functions take place within tightly controlled parameters, including pH, which is managed in part through the ventilatory chemoreflex. This reflex is mediated by central respiratory chemoreceptors (CRCs) specialized to detect blood pH/CO2. Two neuronal populations are thought to mediate this response: the serotonergic (5-HT) neurons of the medullary raphé, and the Phox2b expressing neurons of the retrotrapezoid nucleus (RTN). These groups are both responsive to CO2 stimuli in vivo and in vitro. There are also apparent one-way connections from the raphé to the RTN, which is sensitive to 5-HT. Due to its complex innervation, study of RTN neurons while isolated from other cells, especially 5-HT neurons, has been limited. Here, we developed a culture model that simplifies this circuit, limiting cell types to those found in the rostral ventral medulla. This protocol yielded healthy RTN and 5-HT neurons in vitro, as well as other cell types from that area. Upon study with patch-clamp electrophysiology, cultured RTN neurons responded to CO2 and 5-HT in similar ways to what is reported for different RTN neuron preparations. Using this model, RTN neuron chemosensitivity was significantly decreased during application of 5-HT7 antagonists (SB258719, SB269970) and a 5-HT2A antagonist (MDL 11,939). The effect of 5-HT7 antagonists was recapitulated in slice recordings. Therefore, signaling at 5-HT7 and 5-HT2A receptors is necessary for RTN neuron chemosensitivity. Exogenous 5-HT application also increased RTN neuron firing rate without potentiating the response to CO2, most likely indicating that the necessary 5-HT stimulation must come from neurons that can alter their activity during acidosis. We conclude that RTN neuron chemosensitivity is largely driven by chemosensitive 5-HT neurons, and should be considered an integrative or relay center, rather than an independently chemosensitive one.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains v, 77 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

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In this paper, a 16-cell direct methanol fuel cell (called DMFC) stack was developed to power or charge a mobile phone without any voltage transformer. The various types of the performance decay of DMFCs are studied before a 16-cell DMFC stack is made. The decays due to improper storage are found and avoided. The influences of the MEA treatments on the performance are also studied. Eventually, we try to find the best storage and treatment methods to keep stacks in a good condition all the way. In order to solve the problem of methanol crossover lead to the cathode poisoned, it is necessary to operate under the proper methanol concentration and to discharge before finishing the whole experiment. It is also necessary to maintain MEAs in proper wetness so that the performance will not decline during storage. Additionally, the catalyst in the cathode will use Pt/Ru to replace Pt. This 16-cell DMFC stack is composed of two 8-banded MEAs and 16 carbon fiber bunches. Each MEA is made with 8 sets of electrodes on a piece of membrane. The stack with 16 cells will be connected in series outside of the reaction chamber. The weight and volume of this 16-cell DMFC stack are 55 g (not including 20 c.c. methanol solution) and 99 cm3. The total electrode is 50 cm2 (16-cell¡Ñ3.15 cm2 per cell). The power at voltage 4V is 1680mW when it is operating at room temperature and air breathing. The maximum power density can reach 33 mW/cm2. The specific power density is 22 mW/g and the volumetric power density is 16.9 mW/cm3. This stack can power or charge a mobile phone directly.

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