published_or_final_version / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

published_or_final_version / Medicine / Master / Master of Medical Sciences

Purpose: The purpose of this study was to assess whether the factors historically presented in the literature to differentiate vocal cord dysfunction (VCD) from breathing difficulties of other etiologies accurately predict and identify patients who have VCD. The researchers were also interested in whether patients with VCD have a higher risk of misdiagnosis than patients with breathing difficulties of other etiologies. Finally, the present study investigated whether patients with VCD were more likely to have their symptoms attributed to psychological factors than patients with breathing difficulties of other etiologies. Method: A survey comprised of 23 questions regarding the participants’ previous and current diagnoses, triggers that precede breathing difficulty, and whether or not the participants have ever been misdiagnosed was posted to internet support groups, websites, blogs, and forums. The final participant pool included 20 participants with VCD and 25 participants with asthma. Results: None of the factors investigated accurately differentiated participants with asthma from participants with VCD one hundred percent of the time. However, participants with VCD were more likely to report throat tightness during an attack, association of an attack with symptoms of acid reflux, and rapid resolution of symptoms without treatment. Conversely, participants with asthma were more likely to report expiratory stridor and chest tightness, full resolution of symptoms with use of asthma medications, nocturnal symptoms or symptoms just after waking, and symptoms that seemed to be triggered by environmental agents or allergens. Preliminary findings from the present study suggest that patients with VCD are both more likely to receive a misdiagnosis and have their symptoms attributed to psychological factors than participants with asthma. Conclusion: A diagnosis of VCD must be made very carefully, ideally with instrumental evaluation of the vocal mechanism during an acute “attack” of breathing difficulty. The factors identified in the literature to differentially diagnose patients with asthma from patients with VCD do not accurately differentiate these populations. These findings suggest that continued education about the nature of VCD and differential diagnosis should be paramount to medical professionals. / text

External nuclear medicine diagnostic imaging of early primary and metastatic lung cancer tumors is difficult due to the poor sensitivity and resolution of existing gamma cameras. Nonimaging counting detectors used for internal tumor detection give ambiguous results because distant background variations are difficult to discriminate from neighboring tumor sites. This suggests that an internal imaging nuclear medicine probe, particularly an esophageal probe, may be advantageously used to detect small tumors because of the ability to discriminate against background variations and the capability to get close to sites neighboring the esophagus. The design, theory of operation, preliminary bench tests, characterization of noise behavior and optimization of such an imaging probe is the central theme of this work. The central concept lies in the representation of the aperture shell by a sequence of binary digits. This, coupled with the mode of operation which is data encoding within an axial slice of space, leads to the fundamental imaging equation in which the coding operation is conveniently described by a circulant matrix operator. The coding/decoding process is a classic coded-aperture problem, and various estimators to achieve decoding are discussed. Some estimators require a priori information about the object (or object class) being imaged; the only unbiased estimator that does not impose this requirement is the simple inverse-matrix operator. The effects of noise on the estimate (or reconstruction) is discussed for general noise models and various codes/decoding operators. The choice of an optimal aperture for detector count times of clinical relevance is examined using a statistical class-separability formalism.

For years research has demonstrated a varying incidence of medical disorders manifesting with psychiatric symptoms. A relatively conservative estimate of such so called "medical masquerades" is around 10%. It is important to ascertain whether health care professionals are aware of possible medical masquerades perhaps most especially in a mental health center outpatient setting where non-medically trained clinicians are the first line therapists for treatment in the majority of cases. This study set about to find out how aware three types of health care clinicians (psychiatrists, nonpsychiatrically trained medical doctors, and non-medically trained mental health psychotherapists) are of the prevalence of medical masquerades, and whether these three types of clinicians perform differently on three types of clinical vignettes (psychiatric, somatoform, and medical masquerades). Results revealed that all health care professionals surveyed are aware that there are a percentage of medical masquerades in the clinical population. Results also revealed that the three types of clinicians performed differently on the case vignettes.

Alpha-melanotropin (alpha-melanocyte stimulating hormone, α-MSH) exerts its biological action by binding to specific receptors on the outer cell membranes of its target tissues with a high degree of affinity and specificity. Current evidence suggests that this takes place both in vitro and in vivo in both normal and malignant melanocytes. Thus, if it were possible to attach a radioisotope (e.g., ¹²⁵I) to α-MSH, or a suitable analogue, without interfering with the receptor affinity of the hormone, then a radioreceptor assay could be developed which would allow hormone-receptor interaction to be studied in detail. In addition, this radio-labeled melanotropin might be expected to accumulate in melanoma tumors in vivo thus facilitating tumor localization by nuclear imaging methods as has been successfully accomplished for thyroid tumors. The present studies were initiated to develop a radioactive melanotropin with full, or nearly full, biological activity. This labeled melanotropin must be of sufficient specific radioactivity to be suitable as a tracer in a radioreceptor assay and ultimately as a marker for in vivo tumor localization. The studies described herein provide information concerning: chloramine T induced iodination, lactoperoxidase catelyzed iodination, and iodogen induced iodination of α-MSH and certain structural analogues. Radio-labeled derivatives of various melanotropins were prepared using a variety of iodination techniques. Under conditions commonly used for the iodination of other peptides a substantial loss of biological activity of the native hormone (α-MSH) was observed. This loss of hormonal activity was primarily a consequence of oxidation of methinonine and occurred regardless of the oxidant used (chloramine T, lactoperoxidase-hydrogen perioxide, or iodogen). Under similar iodination conditions using 4-norleucine-alpha-melanotropin ([Nle⁴]-α-MSH), satisfactory incorporation of label into the peptide was accomplished without significant loss of biological activity. Data are presented suggesting that this peptide is far superior to α-MSH for use in the preparation of a radioactive melanotropin. Although some success was achieved using [Nle⁴]-α-MSH with all three iodination methods, the simplest and most consistent method involved the use of iodogen followed by purification of the labeled product using high performance liquid chromatography (HPLC). This importance of these studies in the development of a tracer for a radio-receptor assay and for in vivo localization of melanoma tumors is discussed.

No description available.

No description available.

No description available.

No description available.