• An early 'phosphoinositide effect' in poliovirus infected HeLa cells

      Pickard, Cheryl Lewis; Department of Cell and Molecular Biology (1985-06)
    • Early adolescents' physical activity and nutrition beliefs and behaviors in an urban cluster in the southeastern United States

      Hawks, Miranda R.; Department of Physiological and Technological Nursing (2016)
      Obesity in early adolescents is a significant public health problem that has adverse health consequences, to include increasing the risk of developing type two diabetes and hypertension. Factors such as the environment, nutrition, and physical activity contribute to obesity in early adolescents. The purpose of this ethnographic study was to explore the physical activity and nutrition beliefs and behaviors of early adolescents in an urban cluster in the southeastern part of the United States. The researcher recruited early adolescents at a community organization and collected data using three ethnographic methods: semi-structured interviewing, participant observation, and collection of artifacts. Data were analyzed using constant comparative analysis to shed light on the meaning of early adolescents’ communications about their physical activity and nutrition beliefs and behaviors. Themes that emerged from data analysis included recognizing benefits of physical activity and healthy eating, family influences, connecting with the community, peer influences, electronic media influences, and developing a sense of self. This study contributes to nursing science in three ways. First, all early adolescents recognized both physical activity and healthy eating as beneficial for promoting their health and improving the quality of their lives. Second, early adolescents described their mothers as the most influential family member for both their physical activity and healthy eating behaviors. Third, the community organization was identified as the main facilitator of early adolescents’ physical activities within their immediate environment outside their home. These findings explain three different points of entry that the nursing community can use, separately or together, for their health promotion strategies to encourage physical activity and healthy eating among early adolescents.
    • Early Events in the Periovulatory Interval: Steroidogenesis and Proliferation in Macaque granulosa cells

      Fru, Karenne N; Department of Cellular Biology and Anatomy (2006-06)
      The periovulatory interval is defined as the period of time between the ovulatory stimulus and ovulation of the ovarian follicle. It is initiated by a midmenstrual cycle release of luteinizing hormone (LH) from the pituitary and initiates a cascade of events that eventually lead to extrusion of a fertilizable oocyte as well as remodeling of the follicle into the corpus luteum. Previous experiments looking beyond 12hr after the ovulatory stimulus have identified multiple changes to the preovulatory follicle while little is known of the early periovulatory interval. In spite of the paucity of information available about this time period, it was hypothesized that multiple unknown changes occur early in the interval that are critical to normal ovulation and luteinization. Two endpoints were examined in the periovulatory interval; steroidogenic changes as well as mural granulosa cell proliferation. The novel observation of CYP 21 induction was made as well as identification of 11-deoxycorticosterone (DOC) synthesis in response to hCG both in vivo and in vitro. Additionally, mineralocoritoid receptor (MR) is expressed by granulosa cells thus establishing their potential for corticosteroid sensitivity. Antagonism of MR ablates the normal synthesis of progesterone in response to hCG although the mechanism remains unclear. It was also concluded that even though mural granulosa cells are less likely to proliferate in response to exogenous stimulus in the form of epidermal growth factor (EGF) after hCG, proliferation can be enforced in even luteinizing granulosa cells using insulin. Moreover, mural granulosa cells express EGF family members in response to hCG and express EGF receptor constitutionally. However, more work needs to be done to elucidate the absence of EGF driven proliferation in luteinizing but not non-luteinized granulosa cells.
    • Early Life Environmental Exposure and Hormonal Exposure and Race-Related Influence on the Human Stem Cell Populations in Fibroid and Myometrial Tissues Lead to Compromised Genomic Integrity and Increased Tumorigenesis

      Prusinski Fernung, Lauren; Department of Neuroscience and Regenerative Medicine (5/22/2018)
      Though benign, uterine fibroids (UF) are the most significant benign neoplastic threat to women’s health and most common indication for hysterectomy. The elusive etiology of UF inhibits significant improvement in quality of care for affected women. Somatic mutations in the MED12 gene are currently thought to arise in myometrial stem cells (MSCs) converting them into UF tumor-initiating cells. Defective DNA repair increases the risk of tumorigenic somatic mutations, suggesting that additional mutations arising in fibroid stem cells (FSCs) ultimately contribute further to tumor growth and development. In addition, a significant ethnic disparity exists in UF prevalence, occurring in African American (AA) four times more as compared to Caucasian (CA) women, a phenomenon that has been observed for more than 120 years, but the molecular attributes behind UF’s ethnic disparity are still not fully realized. Our goal is to determine the mechanism by which the physiology of these human uterine MSCs is altered by changes in utero during early development of the epigenetic regulators of DNA-damage repair genes and how these stem cells lead to the origination of MED12 mutations and, ultimately, UF development later in adult life. Using a rat model of early-life environmental exposure, in which rats undergoing early uterine development were exposed to an endocrine disruptor, we compared the DNA repair capacity of exposed, "at-risk" myometrial stem cells to those from unexposed animals. In addition, we utilized human myometrial and fibroid tissue samples to characterize the myometrial stem cell populations from normal versus fibroid-containing uteri and compared the DNA repair capacity of human fibroid stem cells to the stem cells of adjacent myometrium. We determined that DNA repair in both exposed rat MSCs and human FSCs was decreased/altered compared to unexposed murine MSCs and human adjacent MSCs, respectively. In exposed rat MSCs, DNA double-strand break (DSB) repair was significantly impaired both in untreated cells and in cells in which DNA DSB damage was induced. Similar phenomena were observed in human FSCs as compared to adjacent MSCs. These data suggest impaired DNA repair in exposed MSCs and in human FSCs may contribute to initiation and perpetuation of UF tumorigenesis.
    • Early Recognition of Patient Problems in Critical Care: An Interpretative Study

      Minick, Ptlene; Department of Physiological and Technological Nursing; American Nurses' Foundation (1992-05)
      Early recognition of patient problems is crucial in the critical care setting, however the process of early recognition remains elusive. The literature reflects growing consensus that expert clinicians routinely use “intuitive knowing” (embodied intelligence) in critical decision-making situations (Benner, 1984; Benner & Wrubel, 1989). The purpose of this study was to gain an understanding of the embedded knowledge used by critical care nurses in the early recognition of patient problems. Heideggerian hermeneutical analysis was chosen as the theoretical perspective and research method because of its usefulness in revealing contextual understanding of obscure constructs. A purposeful sampling technique was used to recruit the 30 critical care nurses as participants for this study from one of two hospitals in the North Georgia area. All 30 participants had a minimum of three years of experience in critical care nursing and were interviewed once. Eight of the participants were interviewed a second time; in addition, two key participants reviewed and confirmed the interpretation for a total of 40 interviews. Two patterns considered constitutive of the nurses’ Being were found implicitly and explicitly in every interview and were entitled: (a) the perception of early recognition: engendered through care and (b) practical knowing: embodied intelligence. Major themes that were identified were: (a) experience is requisite for early recognition, (b) communication between nurses and physicians, (c) technology: help or hindrance and (d) what sustains me in nursing. A meaningful understanding of process of early recognition of patient problems contributes to nursing science, nursing education and most importantly, to the improvement of patient care.
    • The Effect of a Brief Relaxation Response Intervention on Physiologic Markers of Stress in Patients Hospitalized with Coronary Artery Disease

      Johns, Robin F.; Department of Physiological and Technological Nursing (2009-05)
      Activation of the neuroendocrine response to stress results in numerous physiologic changes that can have an untoward effect on glucose levels and hemodynamic status, especially in the patient hospitalized with coronary artery disease (CAD). This experimental study tested the effects of a brief, nurse-delivered relaxation response (RR) intervention on physiologic markers of stress including capillary blood glucose (CBG), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and rate-pressure product (RPP) in addition to self-reported stress levels (SRSL) in patients hospitalized with CAD. In this randomized clinical trial, subjects (n = 48) were assigned to either the experimental or control group. Pretest measures of CBG, HR, SBP, DBP, RPP and SRSL were obtained for all subjects. Subjects in the experimental group were taught to elicit the RR and asked to practice the technique for 20 minutes. Subjects in the control group were instructed to rest quietly for 20 minutes. Posttest measures of CBG, HR, SBP, DBP, RPP and SRSL were obtained for all subjects following the 20 minute study period. Multivariate analysis of covariance (MANCOVA) demonstrated a significant difference in adjusted mean scores between the experimental and control group (p = .002). Follow-up univariate analyses of covariance demonstrated significant decreases in CBG (p = .008), HR (p = .024) and RPP (p = .044) in the group receiving the relaxation response intervention. The findings indicated that in patients hospitalized with CAD, a brief, nurse-delivered relaxation response intervention was more effective in lowing CBG, HR and RPP than a usual care approach. Thus, a brief, nurse-delivered relaxation response intervention may prove a novel method for hemodynamic and metabolic modulation of the stress response to include the prevention and treatment of stressinduced hyperglycemia among patients hospitalized with CAD.
    • The Effect of a Tobacco Cessation Service-Learning Project on CNL Student Knowledge, Confidence, Beliefs, and Intentions to Intervene with Tobacco Dependent Pregnant Women

      Inglett, Sandra B.; Department of Physiological and Technological Nursing (2011-10)
      This dissertation was a three group comparison study about the effect of a tobacco service-learning project, known as COMMIT (Circle of Motivated Moms for Infants to be Tobacco-Free), has on CNL (Clinical Nurse Leader) student’s knowledge, confidence, and Theory of Reasoned Action beliefs to intercede and educate pregnant women and/or patients. This was compared to CNL students who did not participate in a tobacco cessation service-learning project but were at the same point in their coursework and new CNL students who are just beginning their course of study. Using the Theory of Reasoned Action as a framework the Rx for Change: Clinician-Assisted Tobacco Cessation Pre/Post Test Survey was administered to 70 CNL students divided among 3 Groups. Group 1 (COMMIT) consisted of 14 CNL students, Group 2 (students at the same point in education but without a tobacco service-learning project), and Group 3 (CNL students at the beginning of their program). Factors such as demographics, knowledge, self-efficacy, confidence, control beliefs, subjective beliefs, normative beliefs, and perception of service-learning project were examined in relation to the dependent variable intentions. Qualitative data gained from structured interviews was analyzed for themes from Group 1 and Group 2. Five themes were identified and consistent between Group 1 and Group 2. They were: 1) translational, 2) student value, 3) patient value, 4) awareness, and 5) frustration. The quantitative findings revealed that Knowledge, Confidence to Counsel, and Intention scores had significant effects. There were no effects for Ability to Counsel, Subjective, Normative, or Control Beliefs. There was no correlation between the SELEB (Service-learning Benefit) scale and Intentions to Intercede nor was the regression analysis significant between SELEB and Intentions. However, there were significant correlations between SELEB and Confidence to Counsel, Ability to Counsel, Subjective Beliefs and Control Beliefs.
    • Effect of an Er,Cr:YSGG Laser on P. Gingivalis-Contaminated Titanium Alloy Dental Implant Surfaces In Vitro

      Strever, Jason; Department of Oral Biology (2016-04)
      Implant dentistry has become a widely accepted modality to replace missing teeth. However, dental implants are susceptible to biofilm-mediated inflammatory lesions (peri-implant mucositis / peri-implantitis), similar to that seen around natural teeth (gingivitis / periodontitis). These lesions, in turn, threaten the longevity of implants as anchors for dental prostheses. Because of the similarity in etiology and presentation, comparable treatment modalities are applied to resolve peri-implant and periodontal inflammatory lesions. Such a shared treatment includes mechanical debridement, with or without surgical repositioning of the soft tissue complex. However, most contemporary dental implants feature threads to engage the alveolar bone and a micro/nano-textured surface to stimulate bone-implant contact (osseointegration). Therefore, when the implant threads become exposed and contaminated by biofilm, subsequent surface debridement / decontamination becomes considerably more complex than with that of a natural tooth, which is usually debrided using a metal curette or ultrasonic device. The micro/nano-textured surface of a dental implant is easily damaged by instrumentation using a metal curette. If an efficient method of dental implant surface decontamination could be established, then clinical protocols may be developed that effectively clean the implant surface to achieve peri-implant tissue health. To this end, lasers have been introduced; however, directly applied laser energy may also affect implant surface characteristics, including micro/nano-structure and composition, essential to osseointegration. Therefore, lasers may have disadvantageous clinical effects, in turn compromising peri-implant tissue consolidation and health: the very aspects its use is attempting to provide. Commercially available Er,Cr:YSGG lasers have been used to remove such implant-attached deposits, however the efficacy in removal of bacteria and the safety to the implant surface integrity have yet to be demonstrated quantitatively.
    • The Effect of Blood Flow Rate on PMN Adherence and Protection Against Injury in the Isolated Blood Perfused Canine Lung Lobe Stimulated with PMA

      McCloud, Laryssa; Department of Cellular Biology and Anatomy (1998-05)
      In the lung neutrophil (PMN)-endothelial interactions contribute to the endothelial damage that occurs in many disease states, such as the adult respiratory distress syndrome (ARDS). Current literature states that PMN adherence is greater at low blood flow rates. How high blood flow rates affect PMN-mediated injury in the lung has not been investigated. This study was designed to determine the effects of increased blood flow on the ability of phorbol myristate acetate (PMA) to cause lung injury in the isolated canine lung lobe and on the ability of agents to protect against this injury. Injury was assessed by examining luminal endothelial bound angiotensin converting enzyme (ACE) activity, pulmonary vascular resistance (PVR), pulmonary artery pressure (Pa), double vascular occlusion pressure (Pdo), and the capillary filtration coefficient (Kf). PMN sequestration was measured using circulating white blood cell counts [WBC] and differentials and 51Cr labeled PMN retention by the lung. Lung lobes were perfused at low flow (LF, 0.599±0.001 L/min) or high flow (HF, 1.185±0.004 L/min) and divided into four groups. Group I, LF PMA, Group II, LF Control, Group III, HF PMA, and Group IV, HF Control. Groups I and III received PMA (10* M) while Groups II and IV were treated with the PMA vehicle. PMA decreased ACE activity and [WBC] at both flows while Pa, PVR and Kf were increased. PMA caused lung injury independent of blood flow rate. Isoproterenol (ISO) has been shown to protect against some forms of lung injury. To study the effect of flow rate on the ability of ISO (10*SM) to protect against PMAinduced injury, lobes were perfused at either 0.603±0.003 or 2.015±.0.064 L/min and were pretreated with either saline (Group I, LF Vehicle + PMA) and (Group II, HF Vehicle + PMA) or ISO (Group III, LF ISO + PMA) and (Group IV, HF ISO + PMA) for 20 min before PMA. After PMA Group I and II lobes showed significant decreases in ACE activity and increases in Pa and PVR. Kf measurements after injury could be completed in only three of the six lobes in Group II due to severe edema. Pa and PVR increased after injury in Group III lobes. In Group IV lobes ISO protected against the increases in Pa and PVR and decreases in ACE activity but caused an increase in Kf that was further increased after PMA. Thus, ISO protected against endothelial ectoenzyme dysfunction and partially protected against hemodynamic changes after PMA in lungs perfused at high blood flow rate. Lobes perfused at a low flow rate were not protected from the hemodynamic effects of PMA by ISO pretreatment. Pentoxifylline (PTX) is another agent reported to provide protection against various forms of lung injury. To study the ability of PTX (10'3M) to protect against PMA-induced injury, lobes were perfused at low flow (LF, 0.601±0.002 L/min) or high flow (HF, 1.170±0.005 L/min) and divided into four groups. Group I, LF PTX Control, Group II, LF PTX + PMA, Group III, HF PTX Control, and Group IV, HF PTX + PMA. Lobes were treated with PTX 30 min before PMA or vehicle. [WBC] and blood smear differentials were performed. PTX increased [WBC] in all groups but did not change any other measured parameters. In the presence of PTX, PMA resulted in no changes in ACE activity, Kf or hemodynamic parameters. PMA decreased [WBC] (P<0.05) in both th epresence and absence of PTX. PTX provided protection against PMA-induced lung injury at both flow rates. The injury to PMA was found to occur in lung lobes perfused at both high and low flow. PMA increased Pa, PVR and the Kf while decreasing circulating WBC counts, circulating PMN counts, A ^ /K ^ , and % metabolism of 3H-BPAP. Although the injury to PMA was found to occur independently of flow rate, the ability of ISO to protect against PMA-induced injury was found to be greatest during high flow perfusion. At high flow, ISO completely protected against increases in Pa, Pdo and PVR while attenuating the increase in the Kf. Plasma cAMP levels were also significantly increased by ISO pretreatment and were not altered by PMA in the high flow group. At low flow ISO did not prevent PMA-induced increases in Pa, Pdo or PVR. ISO did however protect against increases in the Kf and tended to increase plasma cAMP levels. Unlike ISO, PTX provided protection against PMA-induced lung injury independently of flow rate. During both high and low flow perfusion PTX protected against PMA-induced increases in Pa, PVR and the Kf while protecting against decreases in ACE enzyme activity. PTX caused the release of WBC from the lung significantly increasing both total WBC and PMN counts. PTX did not prevent the sequestration of PMN or the release of superoxide in response to PMA.
    • Effect of chronic oral treatment with risperidone or quetiapine on cognitive performance and neurotrophin-related signaling molecules in rats

      Poddar, Indrani; Department of Pharmacology and Toxicology (8/7/2018)
      Antipsychotic (APs) drugs are among the top selling pharmaceuticals in the world and they have a variety of important therapeutic applications for neuropsychiatric disorders. However, there are a number of controversies related to this class of agents and many of the relevant questions are difficult to prospectively address in the clinical trial environment. For example, there have been multiple clinical trials for pro-cognitive agents in schizophrenia that have failed; however, the question of how chronic prior treatment with APs might influence the response to a pro-cognitive agent was not addressed. Moreover, there is clinical evidence that chronic treatment with some APs may lead to impairments in cognition, however, this issue and the potential molecular mechanisms of the deleterious effects have been not been prospectively addressed. Accordingly, the purpose of the work described in this dissertation was to prospectively address each of these issues in animals (specifically rats) were environmental conditions can be rigorously controlled. In each of the manuscripts included in this dissertation, two of the most commonly prescribed APs, risperidone and quetiapine were evaluated. In the work conducted in Manuscript 1, we established a therapeutic relevant dosing approach for rats (oral administration in drinking water) and reinforced the argument that these two APs are not pro-cognitive agents. Moreover, we determined that alpha-7 nicotinic acetylcholine receptor (nAChR) ligand like tropisetron has potential as an adjunctive medication in schizophrenia since the pro-cognitive effect was maintained in the presence of chronic AP treatment. In Manuscript 2, we concluded that chronic treatment with risperidone or quetiapine in rats can lead to impairments in a domain of cognition (recognition memory) that is commonly altered in neuropsychiatric disorders. Moreover, the negative effects of the APs appeared to be exacerbated over time. In Manuscript 3, we concluded that risperidone and quetiapine when administered chronically to rats have the potential to adversely affect neurotrophin-related signaling molecules that support synaptic plasticity and cognitive function. These data would suggest that the extensive prescribing of these APs across multiple conditions in patients ranging in age from the very young to the very old should be carefully reexamined. Key Words: antipsychotic, cognition, brain volume, schizophrenia, neurotrophin
    • The effect of control on patients' perceptions of noise in an intensive coronary care unit

      Rhodes, Ellen V; School of Nursing (1988-08)
      The purpose of this study was to ascertain if perception of control was effective in reducing noise annoyance in the Intensive Coronary Care Unit (ICCU) setting. The sample consisted of 30 adult subjects admitted to a 16"!"'bed ICCU in a rural 275 b.ed hospital in the southeastern United States. A Noise Annoyance Questionnaire (NAQ) was the instrument utilized to measure noise annoyance. The randomized post-test only experimental design tested the following hypothesis: Patients who are issued earplugs as a means' to control noise will score lower on a scale measuring annoyance to noise in the ICCU than will patients who are not issued earplugs. Subjects were randomly assigned to either the experimental group (n=15) or control group (n=15). Experimental group participants were issued earplugs with instructions for their use and applicati.on. At 24 hours post-ICCU discharge, all patients were asked to complete the NAQ. The t-test for independent means revealed no significant difference (R =.06). in the mean noise annoyance scores between the groups; therefore, the hypothesis was rejected. This finding indicates that in this study, the total noise annoyance scores from participants receiving earplugs did not differ from the scores of participants who did not receive earplugs. S.ince the nursing intervention (offering earplugs to ICCU patients) was not effective in this sample of patients, other nursing interventions need to be explored as a measures of control of noise annoyance.
    • Effect of Dehydroepiandrosterone on Ovulation in the Immature Female Rat

      Black, John Bryant; Department of Endocrinology (1969-06)
      One of. the most common cause~ bf infertility and associated reproductive .disorders encouritered in medicine and in ~eterinary "practice is the c·ystic ov·ary. The precise factors causing the development of ovarian cysts are ill under~tood brit the delicate balance which exists bet\veen the pituitary and .the gonad is involved. In addition, excessive.androgen production frequently results in similar cystic changes ~pppled ~ith ovulatory ·faiiure. J.Jong term administration of DBA to immature female· rats resulted in one precqcious ovulation followed by ovulatory failure and cystic ovarian changes. Discontinuation of the androgen pro~uced. a ~eries of irregular cycles followed by the resumption of normal cyclic estrus. After the first several days of treatment gon~dotrophin levels remained tonic, indicating that the initial effect of the androgen occurred soon after axial exposure. This possibility was investigated with a series of short ter~ experiments in which 60 mg/kg of DHA was· administered to immature female rats beginning on day twenty..,.seven of age. Precocious ovulation was observed both in animals with and without PHS priming. Gonadotrophin values remained tonic in the DHA + PMS groups, however, a significant pituitary depletion of LH was found .prior to ovulation when DHA was given alone. Inhibition of ovulation iri the DHA + PMS group by sodium-phenobarbital indicatedthat endoienous gonadotrophins were involved even though no depletion could be demonstrated. In "this case tonic glandular .levels must be taken as evidence of increased hypophyseal synthesis. Although present assay methods do not allow an overly specific pi~-pointing of androgen action at the hypothalamic-pituitary level, they do indicate a disruption in nor~~l rhythmic activity. It is reasonable that this disruption is sufficient to cause ovulatory failure and cystic ovarian modification.
    • Effect of Homocysteine on Bovine Aortic Endothelial Cell Function

      Jin, Liming; Department of Pharmacology and Toxicology (2001-05)
      Hypothesis: In hyperhomocyst(e)inemic states, oxidative stress resulting from elevation of homocyste(e)ine levels leads to a decrease in L-arginine transport activity and a decrease in intracellular L-arginine availability. This will in turn limit NO production and increase superoxide production from eNOS. Therefore, the oxidative stress will be increased in endothelial cells, which may eventually lead to endothelial dysfunction and predispose to atherothrombosis. SPECIFIC AIMS 1. Characterize the cationic amino acid transport systems in bovine aortic endothelial cells (BAECs). 2. Examine the effect of HCY on L-arginine transport over time. 3. Determine the influence of oxidative stress, which is produced by HCY, on L-arginine transport. 4. Determine the effect of HCY on endothelial cell membrane potential. 5. Determine effect of HCY on expression of the transport protein CAT-1. 6. Determine the effect of HCY on eNOS activity, eNOS protein levels and NO formation. 7. Determine the effect of HCY on the production of 3-nitro-tyrosine, a marker for production of peroxynitrite. 8 . Determine the effect of HCY on vascular responses to acetylcholine.
    • The effect of hospital preparation on anxiety and fear levels of school-age children

      Wallom, Lynne; School of Nursing (1987-09)
      The purpose of this study was to determine the effectiveness of a hospital preparation program in the reduction of anxiety and fear in school-age children. A quasi-experimental design was us~d •. This study found that the videotaped. preparation program (Appendix F) did not produce significantly lower anxiety and medical fear levels in children viewing the videotape when compared to children who -did. not view the videotape. The results further suggest that there is a positive relationship between anxiety and fear of medical experiences in school-age children who are hospitalized. Children in this study who reported a high degree bf anxiety also tended to report high fear levels at all times. The Pearsori prciduct' moment technique was used to determine cor~~lations for selected variables~- A two-way repeated measures multiple analysi~ of variance procedure was used to examine changes in the children's fear and anxiety over time during hospitalization. The significant level for the rejection of the ·hypotheses· for this: study.was .05.
    • The Effect of Leucite Crystallization and Thermal History on Thermal Expansion Measurements of Dental Porcelains

      Khajotia, Sharukh S.; Department of Oral Rehabilitation (1997-07)
      Objectives. Measurement of thermal expansion in glassy materials is complicated by thermal history effects. The purpose of this research was to determine whether the occurrence of structural relaxation in glassy materials, such as dental porcelains, an changes in porcelain leucite content could interfere with the accurate measurement of the coefficient of thermal expansion during the thermal expansion measurement itself. Methods. In a randomized design, thermal expansion specimens were fabricated using six commercial body porcelains and the leucite-containing Component No. 1 frit (Weinstein et al. patent, 1962), and subjected to one of the following heat treatments: a single heating run at 3°C/min in a conventional dilatometer followed by air quenching; three successive low-rate heating and cooling thermal expansion runs at 3°C/min in a conventional dilatometer; or three successive high-rate heating and cooling thermal expansion runs at 600°C/min in a laser dilatometer. The remaining specimens were left untreated and served as controls. Potential changes in porcelain leucite content were monitored via quantitative X-ray diffraction. Thermal expansion data for each run over a temperature range of 25-500°C and the leucite content of all specimens were subjected to repeated measures analysis o f variance. Results. The thermal expansion coefficient measured on first slow heating was significantly lower than the values for succeeding low-rate heating and cooling runs in all materials (p < 0.001). The high-rate thermal expansion coefficient obtained on first heating was not significantly different from the values of succeeding heat and cool runs in all materials (p > 0.0S). No significant effect of dilatometer thermal treatments on leucite content (p > 0.05) was shown for all materials studied using both dilatometers. Significance. The crystallization of additional amounts of leucite during thermal expansion runs can be ruled out as a possible interference in the determination of the thermal expansion coefficient of dental porcelain. Conventional dilatometer measurements exhibited structural relaxation during the first heating run, as evidenced by the significant difference between the first heating and subsequent runs, while the laser dilatometer measurements were not affected by this thermal history effect. Therefore, high-rate dilatometry provides a more accurate thermal expansion measurement that is free of interference from structural relaxation and additional leucite crystallization.
    • The effect of memory skills instruction on memory and self-esteem in persons fifty to seventy years of age

      Johnston, Linda W; School of Graduate Studies (1986-12)
      This study examined the effect of a mneumonics oriented memory skills improvement course on.memory functioning and self-esteem in a sample, ~f 31 older adults (mean age = 63.4). Subjects in the experim~ntal group (n=15) participated in six hours of structured small group memory instru~tion, while .th~. control group (n=16) receivea no memory instruction. Analysis of covariance of pre- and post-instruction mean scores for the Wechsler Memory Scale and the Rosenberg Self-Esteem Scale revealed·a significant increase in both memory (p=.Ol} and self-esteeci (p=.04) in the experimental group;: no significant improvem~nt on either measure was seen in the control group, nor was a significant correlation demonstrated between memory and self-esteem. The results of this study indic~ted· that a mneumonics oriented course of memory instruction can provide an· effective nursing intervention to assist the elderly in coping with some of the effects of memory loss associated with normal aging.