The role of serotonergic (5-HT) neuromodulation in respiratory chemosensitivity

Thesis (M.S.) University of Alaska Fairbanks, 2007Breathing must be regulated to maintain appropriate levels of oxygen and carbon dioxide. Breathing may be influenced by serotonergic (5-HT) neurons, sensitive to CO₂, which activate the brain's respiratory network. However, this role of 5-HT neurons as CO₂-sensitive chemoreceptors in unanesthetized animals is unclear. This study used an unanesthetized in situ perfused rat brainstem preparation to test the hypothesis that 5-HT neurons contribute to CO₂ ventilatory responses. Changes in phrenic nerve discharge patterns were monitored as gas-saturated solutions supplying the preparation were switched from 5%C0₂ to 7%C0₂ (balance 0₂). The importance of 5-HT neurons was identified by comparing responses before and after application of the specific serotonin 1A receptor agonist 8-hydroxy-(dipropylamino) tetralin hydrobromide (8-OH-DPAT; at doses of 0, 1.5, 3, and 6 uM in the perfusate). The action of 8-OH-DPAT is to inhibit 5-HT neurons and reduce synaptic 5-HT release. Results indicated that changes in phrenic burst pattern similar to hypercapnic ventilatory responses observed in vivo, were greatly disrupted by 8-OH-DPAT treatment. These results illustrate that activation of 5-HT neurons is critical for CO₂ chemosensitivity in this in situ preparation and suggest that these neurons may play a key role in the regulation of breathing in otherwise intact animals.1. Neural control of breathing -- 1.1. Respiratory pattern generation -- 1.2. Neuromodulation and chemosensitivity -- 1.3. Serotonergic neurons and chemosensitivity -- 1.3.1. Chemosensitivity of serotonergic neurons -- 1.3.2. Location -- 1.3.3. Connectivity -- 1.3.4. Serotonergic neuromodulation -- 1.4. 5-HT₁a receptors -- 1.5. Chemoreceptor controversy -- 1.6. Hypothesis -- 2. Materials and methods -- 2.1. Perfused rat brainstem preparation -- 2.2. Recording of neural activity -- 2.3. Protocol -- 2.4. Responses to hypercapnia -- 2.5. Responses to hypercapnia following serotonin block -- 2.6. Data analysis -- 3. Results -- 3.1. Initial conditions -- 3.2. Hypercapnic response -- 3.3. Time controls -- 3.4. Dose dependant response -- 3.5. Influence of 8-OH-DPAT -- 4. Conclusion -- 4.1. Eupnea -- 4.2. Frequency and Te increase with hypercapnia -- 4.3. Effect of 8-OH-DPAT on burst pattern during normocapnia -- 4.4. Effect of 8-OH-DPAT on respiratory response -- 4.5. Mechanisms -- References

Junior Recital: Kait Fieldman, Trumpet; Patricia Foltz, Piano; October 24, 2009

Kemp Recital HallOctober 24, 2009Saturday Afternoon1:30 p.m

Optimization of Process Parameters for Reentrant Surfaces in Direct Metal Laser Melting

One of the key factors for development and optimization of direct metal laser melting (DMLM) is the analysis of process parameters on reentrant build geometry and surface finish. Recent studies have focused on the optimization of standard build parameters with only minor emphasis on reentrant geometries. Parameters that are not optimized often contribute to poor surface finish, difficult to remove supports, and failed-to-build geometries of reentrant surfaces that limit the capabilities of DMLM. Through the analysis of multiple studies with varying process parameters and input scan path geometry, open loop methods for creation and control of reentrant build geometries are assessed and presented.Mechanical Engineerin

Young women of color : Flourishing despite discrimination and depression

Background. Flourishing is negatively related with depression, but has been proposed as a separate axis and an independent aspect of overall mental health. One factor that has been shown to affect both depression and flourishing is racial discrimination. This study hypothesizes that, in young undergraduate women of color, discrimination experiences will be negatively associated with flourishing, even after accounting for the known negative associations between discrimination experiences and depressive symptoms. Method. Women (n = 109), few of whom identified as White non-Hispanic, completed baseline surveys regarding depressive symptoms, flourishing, discrimination experiences, and SES. Results. Discrimination was significantly associated with depressive symptoms but not flourishing. The relationship with socio-economic status was also explored, and SES was found to be a significant predictor of flourishing. Additionally, discrimination experiences and SES were related and were not independent predictors of depressive symptoms. Discussion. Despite no association being found between flourishing and discrimination, results still indicated that discrimination may be harmful to mental health as it was positively correlated with depression. Also, it was found that SES may be associated with the ability to flourish, indicating that SES may affect mental health. Key Words: Flourishing, Discrimination, Depression, Psycholog

Exploring the Feasibility, Validity, and Reliability of DIGEST after Maxillectomy

https://openworks.mdanderson.org/sumexp23/1016/thumbnail.jp

Corporate Governance and Disclosure of Information on Corporate Social Responsibility: An Analysis of the Top 200 Universities in the Shanghai Ranking

Corporate Social Responsibility (CSR) and its disclosure in the university environment is a topic of current relevance, as it makes the entities’ commitments visible and provides indicators that enable them to improve the institution management and communication with stakeholders. The goal of this study is to determine to what extent the structure and mechanisms for governance and the demands of stakeholders influence policy for disclosing CSR information, both in general (more related to a strategic perspective) and specifically (more focused on specific social, environmental, economic, and educational issues). The results of our analysis of a sample of the top 200 universities in the Shanghai Ranking show no association of the profile and gender of the university’s rector and frequency of board meetings with CSR disclosure policy, but leadership team, the size of governance board, committees in the governance board and stakeholder participation are factors determining disclosure of information on matters of CSR. The results show that proximity to the day-to-day, diversification of functions, and communication with interest groups are crucial to transparency and disclosure of CSR information.This research was funded by R&D PROJECTS. EUROPEAN REGIONAL DEVELOPMENT FUND (ERDF) ANDALUSIA 2014-2020 OPERATIONAL PROGRAM, grant number B1-SEJ-387-UGR1