Experiments were performed to elucidate the mechanisms contributing to the hyperbaric bradycardia. Ethical approval was obtained and all subjects gave written and informed consent. Heart rate, arterial blood pressure, respiratory activity and carotid sinus baroreceptor reflexes were monitored non-invasively. Four healthy male saturation divers were compressed to 46ATA. Significant reductions in resting heart rate, mean arterial pressure, systolic blood pressure and diastolic blood pressure were observed. Baroreceptor sensitivity was significantly increased at 46ATA. A separate series of investigations determined the effects of breathing an increased gas density and an increased partial pressure of oxygen (<I>P</I>₀₂) on arterial blood pressure, heart rate and baroreceptor sensitivity at 1ATA. Two groups of 6 healthy male subjects participated in the experiments. No significant changes in resting heart rate, arterial blood pressure, respiratory rate, tidal volume or baroreceptor sensitivity were observed breathing an increased gas density up to 5.47gl^-1. Raising the inspired <I>P</I>₀₂ to 0.5bar at 1ATA resulted in a significant reduction in resting heart rate and a significant increase in carotid sinus baroreceptor sensitivity. Respiratory sinus arrhythmia (RSA) was used as a non-invasive estimate of vagal tone to determine whether the hyperbaric bradycardia is associated with changes in vagal autonomic control. No changes in the overall magnitude of RSA were observed over a range of respiratory rates at high pressure compared to controls at 1ATA. These results suggest that increased gas density is not a contributing factor but increased <I>P</I>₀₂ may play a role in the development of hyperbaric bradycardia.

Thesis--Oslo. / Includes reprints of six supporting articles. Includes bibliographical references.

Thesis--Columbia University. / Vita. Bibliography: p. 45-51.

Thesis--Oslo. / Includes reprints of six supporting articles. Includes bibliographical references.

Thesis (doctoral)--Ludwig Maximilians-Universität zu München, 1979.

Mainz, University, Diss., 2003.

With the continuous evolution of sinus augmentation procedures in the field of implant dentistry it is imperative to have a comprehensive understanding of the maxillary sinus area. Both lateral wall and crestal approach sinus augmentation procedures have proven to be extremely successful for guided bone regeneration in the maxillary sinus. However, complications stemming from augmentation procedures are related to the presence of pre-existing maxillary sinus pathologies. The purpose of this study was to expand upon the current knowledge base in regards to the prevalence of maxillary sinus pathologies in patients presenting to an implant dentistry practice. To this end, computerized tomography (CT) scans of patients presenting to the Misch International Implant Institute (MIII) were analyzed for the existence of maxillary sinus pathology. Scans of 275 patients presenting to the MIII for maxillary sinus augmentation were evaluated by up-to three different examiners, all of whom were calibrated to the study design and well versed in the use of software to analyze CT scans. Age and gender were also evaluated to see if they had any relationship on the incidence of pathology. Scans were classified into one of five categories based upon the type of sinus pathology detected. The categories of sinus findings were: healthy, mucosal thickening > 5 mm, polypoidal mucosal thickening, partial opacification and/or air fluid level, and complete opacification. Overall, 54.9% of scans were classified as healthy, and 45.1% of scans were classified as exhibiting sinus pathology. Men were more likely to exhibit pathology compared to females (p<0.01). However, age did not appear to have any relation on the prevalence of sinus pathology. The prevalence of sinus pathology reported in this study appears to be within the range shown in previous medical and dental literature. However, due to the different populations studied in the literature and the varying definitions of what constitutes pathology, there is no consensus as to the exact prevalence of sinus pathology. Therefore, it may be more important for the dentist who is evaluating a CT scan prior to maxillary sinus augmentation to understand which patients will benefit from referral to another specialist (such as an otolaryngologist) for evaluation and co-management. It is proposed that based on the findings of this study, 45.1% of patients would require further consultation prior to proceeding with maxillary sinus augmentation surgery. / Oral Biology

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Background: Sick sinus syndrome (SSS) is common and may require electronic pacemaker implantation, gene therapy (biopacemaking) may be an alternative. For SSS, repair may be better than the generation of a de novo biopacemaker, due to the complex nature of the sinoatrial node (SAN). We hypothesised that an ex vivo model of SSS could be created by the identification of a subsidiary pacemaker in the SAN region, and that expression of a pacemaker channel (HCN4 or HCN212) in this region would accelerate the pacing rate. Methods: A bradycardic SSS model was generated by the removal of the upper two thirds of a rat SAN and a system to record the intrinsic activity during tissue culture was developed. The leading pacemaker site of the SSS preparations were identified by activation mapping then characterised by If blockade, β-adrenergic stimulation, histology and immunohistochemistry. Further SSS preparations were injected in this region with recombinant adenovirus (RAd) expressing no functional ion channel (Ad5-GFP or Ad5-GFP-HCN4Δ); or RAd expressing a functional If channel (Ad5-HCN212 or Ad5-PREK-HCN4). During tissue culture electrical activity was monitored using bipolar electrodes. Results: Tissue culture and monitoring of the rat SAN is feasible and does not induce significant changes in HCN4 or connexin-43 expression. The uninjected SSS preparations displayed a slower rate than the control SAN (p<0.001). In 5/6 cases the subsidiary pacemaker was HCN4 -ve and Connexin-43 +ve (in contrast to the SAN) and was close to the superior aspect of the inferior vena cava. The cell size of the subsidiary pacemaker was comparable to that of the SAN and smaller than working myocardium (p<0.001). Pacing was responsive to β-adrenergic stimulation and was partially dependent on If current. The pacing rate of the AdHCN212-injected SSS preparations was significantly faster than the uninjected SSS preparations (p<0.001). The remaining RAd did not significantly affect the pacing rate of the SSS model. Conclusions: There is subsidiary pacemaker tissue close to the superior aspect of the IVC that shares some characteristics of the SAN. These results suggest that adenovirus-mediated expression of HCN channels in subsidiary pacemaker tissue of the right atrium may be a useful strategy in biopacemaking for SSS.

Objectives: As cone beam computerized tomography is used more widely for initial data collection and treatment planning, more valuable anatomic information is at the disposal of clinicians. The scans provide a very accurate display of the patient’s anatomy and these beneficial findings can be used to prevent surgical complications as well as advancing anatomical knowledge. This study aims to expand the current knowledge on the location of the infraorbital nerve in relation to the maxillary sinus in a group of patients who had CBCT scans taken for diagnosis and treatment planning. The study also aims to determine if age, gender or ethnicity have a relationship with the location of the nerve in relation to the sinus. Materials and Methods: 821 CBCT scans were take at Temple University Kornberg School of Dentistry Department of Oral and Maxillofacial Radiology from January 1, 2009 to July 31, 2013. These scans were evaluated using i-CAT computer imaging software. Patients under 18, patients without posterior or maxillary dentitions and patients who’s scans did not include the infraorbital nerve were excluded from the study. A total of four hundred three (403) CBCT scans were included in the study. Patients with visible infraorbital nerves were selected and location, age, gender and ethnicity were recorded. Individual scans had infraorbital nerves identified and examined for relationship superior to a specific tooth, and distance above the floor of the sinus. Results: After reviewing 680 scans, only 403 were included in the study due to exclusions. Scans were subdivided into age, gender, ethnicity and location of the nerve in relation to tooth position. The total average distance from the infraorbital foramen to the floor of the maxillary sinus was 23.94 mm on the right side and 22.84 mm on the left side. The average distance of males was 25.3 mm on the right and 24.27 mm on the left. The females’ average distance was 22.77 mm on the right and 21.62 mm on the left. The distance increased as the patients aged. The most common maxillary tooth inferior to the foramen was second premolar 46.65% of time, followed by the first molar 41.69% of the time. The difference between genders, right and left sides, and age groups all showed statistical significance. The differences between the ethnicities were not statistically significant. Conclusion: Based on the data collected and analyzed in the present study, the infraorbital foramen appeared to be located above the second premolar or first molar 88% of the time. The distance of the foramen from the floor of the sinus was larger in men than women. The right and left side can be different, and the distance tends to increase with the age of the patient. This information can be applied to better achieve local anesthetic delivery success, and avoid complications and nerve damage when performing procedures. / Oral Biology