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  • Freeze Filtration: Description and Evaluation of a Method for Obtaining Samples of Liquid Phase From Frozen Solutions

    Bayer, Dirk; N/A (Medical College of Georgia, 1989-09)
    The objective of this study was to develop a method for sampling the liquid phase of frozen solutions (i.e. the remaining liquid between ice crystals and other solids) for subsequent chemical analysis in order to determine the extent of ice formation and other physical-chemical effects of freezing upon solutions. Such information could enhance the development of cryoprotective agents (CP As). which would allow the frozen long term preservation of organs for transplantation. The traditional thermometric/ calorimetric methods for the measurement of ice formation are susceptible to bias by composition change of the liquid phase caused by secondary solid phase formations (i.e. solids besides ice). They are not able to determine the nature Df such composition changes, and some changes, like that of the pH, will go unnoticed. The new method uses subatmospheric pressure to aspirate liquid phase from a cooled sample holder into a collection vial. "Freeze Filtration" has been tested on four well-established cryoprotective agents comparing measurements in this study with literature values on these chemicals. Remarkable accuracy and repeatability have been achieved. Deviations from published values depend on the cryoprotectant used, which suggests a CPA-dependent methodical difference that may be rooted in bias within the literature values. Cells and solute precipitates can be isolated along with liquid phase, and the freeze-elevated concentrations of Na+, K+, Ca2+, and H+ of a single sample have been measured. Freeze Filtration differs from the older methods by providing a simple mode of operation, low cost, the ability to determine composition changes, and the ability to serve as a physical-chemical reference during actual cryosurvival studies. It is directly demonstrated that freezing at velocities and sample sizes applicable to organ freezing can result in substantial pH changes in the liquid phase and the precipitation of solutes. The data also indicate that 1,3-butanediol is not a good cryoprotectant.
  • Mechanisms for Control of Renal Vascular Resistance in Type I Diabetes Mellitus

    Bell, Tracey D.; Department of Physiology; American Heart Association; National Institutes of Health (Medical College of Georgia, 2007-04)
    Glomerular hyperfiltration and an increase in renal blood flow are hallmark characteristics of Type I_ Diabetes Mellitus in the early stages, and are major risk factors for the development of diabetic nephropathy. Previous studies from our laboratory have implicated an important role for the Nitric Oxide system. in mediating this response, because giving nitric oxide synthase inhibitors· 'prevented the increase in renal plasma flow and glomerular filtration rate during diabetes. However, a limitation of. these studies is that single point measurements were taken and may not reflect the time-dependent role of nitric oxide. Therefore, we have developed a more precise method to measure the role of nitric oxide in the chronic control of renal blood flow during diabetes. We measured renal blood flow continuously, 18 hr/day using a Transonic flow probe in control (C) and diabetic (D) rats. Renal blood flow averaged 8.0±0.1 and 7.8±0 ml/min in the .C and D groups, respectively, during the control period and induction of diabetes caused a marked and progressive increase in renal blood flow in the D rats, averaging 10±6% above control on day 1, and 22±3% and 34±1% above control by the end of diabetes weeks 1 and 2. During the control period, glomerular filtration rate averaged 2.1 ±0.1 and 1.7±0.1 ml/min in the C and D groups, respectively. Glomerular filtration rate did not change during the experiment in the C rats, but increased significantly in the D group, averaging 54±21 and 52±19% above control during diabetic weeks 1 and 2 and renal vascular resistance decreased significantly during the diabetic period. There were no significant changes in filtration fraction in either group. Importantly, chronic blockade of nitric oxide completely prevented the increase in renal blood flow and prevented the diabetes-induced hyperfiltration normally associated with diabetes. These data together suggest that nitric oxide is essential for the renal vasodilation caused by onset of type I diabetes and suggest that the renal vasodilation in diabetes occurs primarily at the afferent arteriole. Autoregulation of the afferent arteriole plays an important role in determining glomerular capillary hydrostatic pressure and glomerular filtration. In diabetes, renal autoregulation may be impaired, but the relative roles of myogenic and tubuloglomerular feedback mechanisms in controlling renal blood flow, and the time course of their involvement, is not known. In addition, there is very little known about autoregulatory mechanisms at the very onset of diabetes, before there has been time for renal structural changes to become manifest. Therefore, we designed experiments to establish the role of the myogenic response and tubuloglomerular feedback mechanism in renal blood flow. control at the onset of diabetes. Coupling continuous measurement of renal blood flow using Transonic flow probes and continuous measurement of arterial pressure, we were able to use transfer function analysis to determine the relationship between arterial pressure and renal blood flow .. This type of analysis examines the dynamic ability of the renal vasculature to attenuate, or autoregulate, the influence of the oscillatory power of blood pressure over the range of frequencies at which the myogenic response and tubuloglomerular feedback mechanism operate. In these studies we demonstrated that transfer function gain was negative, indicating effective· autoregulation, in the frequency range of the myogenic (0.1- 0.3 Hz) and tubuloglomerular feedback (0.03-0.06 Hz) mechanisms during control days. However, at the onset ·of diabetes gain increased to positive values and continued through the 2-week diabetic period. Chronic blockade of nitric oxide in diabetic rats normalized the increase in transfer function gain and possibly enhanced the autoregulatory response. Our model provides a novel method to measure the chronic effects of the nitric oxide on renal blood flow control during diabetes. By using this model we have demonstrated that nitric oxide is required for the immediate increase in renal blood flow in diabetes. Furthermore, these data suggest renal autoregulation is impaired at the onset of diabetes and may play a role in the increase in renal blood flow and glomerular filtration rate early in diabetes. In addition, these data together suggest that nitric oxide contributes to the impaired autoregulatory capacity of the renal vasculature.
  • microRNA Regulation of Acute Kidney Injury

    Bhatt, Kirti; Department of Cellular Biology Anatomy (Georgia Health Sciences University, 2011-08)
    Acute kidney injury (AKI) is caused by an injury or insult to the kidneys resulting in abrupt loss of renal function. Acute kidney injury is a highly prevalent disease characterized by high rates of morbidity and mortality mainly due to the absence of effective therapeutic options. Dissecting the molecular basis of AKI is vital not only for understanding the mechanisms of disease pathogenesis, but also for designing effective treatments. The small regulatory non-coding RNAs, microRNAs, are vital regulators of normal cellular function and critical modulators of various pathological conditions. An intense focus has recently emerged on the study of microRNA regulation in the maintenance of kidney function and the development of renal diseases. Our laboratory demonstrated the first evidence that microRNAs play a pathogenic role during ischemia-induced AKI by utilizing a conditional Dicer knockout mouse model. The focus of my work was to identify and functionally characterize novel microRNAs that contribute to AKI. Firstly, using a cisplatin-induced nephrotoxicity model of AKI, we showed that miR-34a is up-regulated in a p53 dependent manner and contributes to renal cell survival. Secondly, we identified a novel microRNA, miR-687, as the most significantly upregulated microRNA during ischemia-induced AKI. Mechanistic studies showed that miR-687 is up-regulated in a hypoxia-inducible factor 1 (HIFl)-dependent manner and 3 subsequently negatively regulates PTEN expression under hypoxic conditions. These studies have unearthed an important HIFl-miR-687-PTEN signaling pathway that regulates cell cycle progression during hypoxia. Thirdly, we show that inhibiting miR- 687 significantly ameliorates ischemia-induced AKI. These studies have identified a pivotal signaling mechanism involved in cellular response to hypoxia that may be targeted for renoprotection during ischemic AKI.
  • Molecular and Biochemical Characterization and Regulation of Folate Transport Proteins in Retinal Muller Cells

    Bozard, Renee; Department of Cellular Biology & Anatomy (Georgia Health Sciences University, 2011-07)
  • The Effect of Filled Adhesive Application Method and Water Storage on the Retentive Features of a Mechanically Retained Ceramic Orthodontic Bracket to Bovine Enamel

    Brooks, K. Glenn; Department of Oral Biology (Medical College of Georgia, 1996-12)
    Ease of bracket application, durability of enamel bond, and formation of an intact peripheral seal to maintain color stability are goals of esthetic, ceramic orthodontic bracket use. PURPOSE This research examined the effect of three different types of photo-curable resin applications to a commercial ceramic orthodontic bracket base on bond strength and potential for microleakage on bovine enamel following various periods of water storage. METH 0 D S Resin adhesive was applied to polycrystalline orthodontic brackets (Transcend 6000, 3M Unitek, Monrovia, CA) using three methods: 1) manual application of a light-curable adhesive (Transbond, 3M Unitek) to the bracket base (no resin); 2) with a coat of unfilled resin prior to adhesive placement (resin); 3) or with adhesive paste pre-applied by the manufacturer (APC Brackets, 3M'Unitek). Brackets were applied to flattened, acid-etched bovine enamel surfaces using standardized loading conditions. Bonded brackets were stored in phosphate-buffered saline at 37 degrees C for the following durations prior to testing: 1 day, 1 week, and 14 weeks. Following storage, the brackets (17 per test condition) were debonded in shear or were stored in basic fuchsin dye for 24 h prior to sectioning and examination for microleakage under stereo magnification (12 teeth per condition). RESULTS Two-way ANOVA indicated that type of adhesive resin application (p=0.0001) and duration of water storage (p=0.0063) were both significant factors on strength: resin (13.4 MPa) > APC (10.9 MPa) > no resin (9.3 MPa). Water storage decreased bond strength for all groups after 14 weeks storage. The primary debond location for all groups was the adhesive/bracket interface. APC brackets showed greatest microleakage (42%) after 14 weeks, while the other groups each leaked in 33% of specimens. The method of resin application to a ceramic bracket base is shown to affect both strength and potential for micro leakage.
  • Signaling in the Late Phase of T cell Activation

    Chang, Jing-Wen; Institute of Molecular Medicine and Genetics (Augusta University, 2004-12)
    Engagement of the T cell antigen receptor (TCR) induces multiple signaling pathways, including the activation of extracellular signal-regulated kinase (ERK), a mitogen-activated protein kinase (MAPK). We previously reported the importance of sustained ERK activation for interleukin-2 (IL-2) production. Inhibition of ERK activation from 2 to 6 hours after TCR stimulation significantly impaired IL-2 production and activation of the nuclear factor-kappaB (NF-KB) family transcription factor, c-Rel, whereas inhibition during the first 4 hours had no effect. Loss of the adaptor protein, She, results in impaired ERK activation during the late phase ofTCR stimulation, and leads to severely reduced IL-2 production and c-Rel activation. These data suggest a novel activation process following TCR stimulation that involves She and late ERK activation-dependent regulation of c-Rel activation and IL-2 production. To further understand the mechanisms underlying this pathway, we employed a two- dimensional differential in-gel electrophoresis/ mass spectrometry (2D-DIGE/MS)-based proteomics approach. This approach to identify members of a She-containing signaling complex revealed alpha tubulin and beta actin as She associated proteins. Furthermore, we identified proteins whose expression and modification are triggered by TCR stimulation and are under control of the ERK signaling pathway, by comparing TCR-stimulated samples with or without MEK (MAPK kinase) inhibitor treatment. Here we report heterogeneous nuclear l ribonucleoprotein K (hnRNP-K) as a novel downstream target of ERK in TCR signaling. Functional studies using small RNA interference showed that hnRNPK regulated IL-2 production at the transcriptional level. We also showed that knockdown ofhnRNP-K expression specifically impaired NF-KB activity, but caused a relatively minor effect on activating protein-I (AP-1) activity and expression of CD69 or CD25. Biochemical analysis showed that knockdown of hnRNP-K caused enhanced proteolysis of the protooncogene Vav. MEK inhibitor treatment during the late phase of stimulation also enhanced proteolysis of Vav. Moreover, knockdown of hnRNP-K impaired Vav-mediated transcriptional activation ofIL-2 gene. T!\ken together, these results indicate that ERK signaling modulates IL-2 production by regulating Vav activity through the function of hnRNP-K. We also examined changes in phosphoprotein profiles upon TCR stimulation and MEK inhibitor treatment. Results obtained from these three different approaches provide a further understanding of the mechanisms that regulate late phase T cell activation as well as the components required for full activation of T cells.
  • A Comparison of the Effects of Childbirth Education Upon Primigravida's Pain Tolerance in Labor

    Collier, Pamela; College of Nursing (Augusta University, 1992-12)
    The purpose of this study was to determine if a relationship exists between attendance at prepared childbirth classes and pain tolerance in labor. The hypothesis tested was: Primiparous women who have attended prepared childbirth classes will demonstrate higher pain tolerance during labor than those women who have not attended any prepared childbirth classes. A prospective repeated measures design was used. Data were collected from primiparous women in labor in the form of a demographic sheet and a visual analogue scale (VAS). A VAS was administered twice during labor, and once postpartum. The sample consisted of 72 subjects divided into Group I (N=26) who attended prepared childbirth classes and Group II (N=46) who did not attend any prepared childbirth classes. These two groups were subdivided further by the type of labor room assignment (LR, Semi-private LR, LDR). The data were analyzed using a repeated measures analysis of variance test (ANOVA) to determine if any differences existed among the two childbirth class groups and the labor room assignment. Chi square was performed on ethnicity, income, and classes. Spearman rank correlation coefficients coefficients were computed to determine if any correlations existed between pain levels and age, school grade, and income. No significant differences were found for between the two study groups in pain level at any time of measurement. A significant ethnicity by time interaction effect was found in pain during labor (p < 0.01). Significant time effects were found for subjects who had epidura1s dosed at Time 1 (p < 0.02), and method of delivery (p < 0.02). A significant negative correlation was found at Time 2 (p < 0.04; r=-0.28) and Time 3 (p < O.O5; r= -0.27) between school grade and pain levels, and at Time 1 between income and pain levels (p < O.O1; r= -0.32).
  • The Effect of Dihydrotestosterone of the Growth and Development of Ovarian Follicles in the Rat

    Conway, Barbara-Ann; College of Nursing (Medical College of Georgia, 1989-05)
  • The Effect of Atrial Pacing on Blood Pressure in Hypertensive Subjects

    Crawford, Lyndia Diana Widgeon; Department of Adult Nursing (Medical College of Georgia, 1992-07)
    This study investigated the relationship between atrial pacing and blood pressure (BP) in hypertensive patients. It was hypothesized that BP and medication requirements would be reduced in patients with constant atrial pacing (CAP). The study design was descriptive correlational. Retrospective chart review was used to examine a nonprobability, convenience sample of 23 subjects with hypertension .(HTN) and atrial pacemakers. Those 1'7ith malignant HTN were excluded. Subjects were divided as to constant atrial pacing (CAP) or intermittent atrial pacing (IAP). BP was recorded before implant, and at 24 hours, 1-3 weeks and 2-3 months post-implant. Repeated measures ANOVA revealed significant differences in the BP of the two groups. T-tests showed differences in the systolic BP at 1-3 weeks (p= 0.04), and 2-3 months (p= 0.03), with lower BP readings in the IAP group. Changes in HTN medications revealed differences in the two groups (using chi square p= 0.03), with the CAP group requiring fewer increases. The hypotheses were not supported.
  • The Effects of Cardiac Rehabilitation on Medical and Surgical Patients

    Dyches, Cathy Ellen; College of Nursing (Medical College of Georgia, 1991-04)
    The Effects of Cardiac Rehabilitation on Medical and Surgical Patients The purpose of this study was to examine the effect of cardiac rehabilitation on self-esteem, exercise capacity, and perceived exercise capacity of ·medical and surgical patients. The sample consisted of 11 men and 6 women between the ages of 32-81 years with a mean age of 56.5 years. All subjects participated in 12 weeks of cardiac rehabilitation. Chi square analysis revealed no significant difference in the groups based upon demographic data. Paired I-tests revealed' that cardiac patients have increased self-esteem (p.=.002); perceived exercise capacity (p = .001), and actual exercise capacity (p = .01) after completing a cardiac rehabilitation program. Analysis of ' covariance indicated that surgical patients do not differ significantly from medical patients in levels of self-esteem, perceived exercise capacity, or actual exercise capacity. Spearman rank order correlation revealed that there was a ' I positive correlation between : self-esteem as measured by the Rosenberg Self- Esteem Scale (RSE) and perceived exercise capacity as measured by the Ference-Gueldner Picture Form of the Ference Field Motion Tool (FGPFFM). Results of the study demonstrated that although medical and surgical patients did not differ significantly in self-esteem and exercise capacity, cardiac rehabilitation programs assist all cardiac patients tested to restore physical capacity and psychosocial functioning.
  • Induction of Inflammatory Proteins in Healthy Periodontal Ligament Fibroblasts by Periodontally Diseased Fibroblasts

    Elmehdawi, Huda R.; Department of Oral Biology (Georgia Health Sciences University, 2011-07)
  • Maternal Substance Abuse, Self-Esteem, and Maternal-Fetal Attachment

    Foster, Angela M.; College of Nursing (Medical College of Georgia, 1994-06)
  • The Effects of Drugs on the Expression of Human Fetal Hemoglobin in a Transgenic Mouse

    Fricks, William P.; Department of Cellular and Molecular Biology, (Medical College of Georgia, 1996-06)
    A transgenic mouse carrying the human locus control region (LCR), the Ay gene, and 13-gh>bin gene on a single construct was treated with hydroxyurea, a-amino butyric• acid, valproic acid, or isobutyramide to determine whether y-globin reactivation in the adult mouse is achievable with drugs. The results from this study indicate that the human y-globingene in the line 17-1 mouse is not inducible. The ineffectiveness of the drugs to stimulate y-globin expression in line 17-1 may be due to the inability of the mouse to synthesize a trans-acting factor which may only be present in the embryonic yolk sac. This study raises questions about the significance of other reports on the inducibility of the human y-globin gene in transgenic mice.
  • Pharmacological Properties of T-Kininogen & T-Kinin

    Gao, XiaoXing; Department of Pharmacology and Toxicology (Medical College of Georgia, 1991-03)
  • Factors That Promote or Inhabit Confrontation of Chemically Impaired Nurses by Nursing Administrators

    Harrell, Lisa G.; College of Nursing (Medical College of Georgia, 1989-06)
  • The Mutual and Individual Role Expectations of Nurses and Physicians

    Hilson, Diane N.; College of Nursing (Medical College of Georgia, 1990-04)
    The purpose of this descriptive, correlational study was to identify the metal and individual role expectations of physicians and nurses, and to identify discrepant perceptions, if any, on the part of one or the other. A total of sixty-five (54%) nurses and 78 (43%) physicians completed the Nurse and Physician Role Questionnaire and demographic data sheet. Two-tailed t-tests were utilized to test each hypothesis and to measure the differences between the nurses' and physicians' perceptions as expressed in each item response. Significant differences were found between the two groups' perceptions of their own role and the role of the other. Physicians differed in their expectations regarding both the nurse's role and their own role more so than did the nurses.
  • The Relationship Between Nurses' Completion of a Pain Management Educational Program and Nurses' Pain Management Behaviors

    Howell, LaDonna W.; School of Nursing (Augusta University, 1995)
    The purpose of this study was to determine if there was a relationship between nurses' completion of a pain management educational program and nurses' pain management behaviors as evidenced by their documentation. Using a pretest/posttest design, the Chart Audit for Pain and the Pain Audit Tool were used to evaluate 136 chart entries by nurses assigned to surgical units. Data were analyzed using the Chi-square statistic. No significant relationship was found between nurses' completion of the pain management program and their documentation behaviors. Based on these findings a single educational program does not appear to be sufficient to change nurses' documentation behaviors regarding pain management. Frequently scheduled programs and administrative involvement in pain management educational plans were encouraged.
  • Regulation of renal medullary endothelin β receptor function by angiotensin II: evidence of sex differences

    Kittikulsuth, Wararat; Medical College of Georgia (Augusta University, 2012-08)
    The renin angiotensin system and endothelin (ET) systems play critical roles in regulating kidney function and blood pressure. Angiotensin (Ang) II exerts its pro hypertensive effects through A Tl receptor activation. ET -1 has similar effects mediated by ETA receptor stimulation. In contrast, ET -1, via ET s receptors, mediates vasodilation, anti-inflammation, and natriuresis. In the clinical setting, hypertension is more common in men than in premenopausal women of the same age. Moreover, in a number of animal models of genetic or experimental hypertension, females are somewhat protected from high blood pressure compared to males. We previously found that hypertensive male rats, induced by chronic Ang II infusion, have impaired ET 8 receptor function. Because ET s receptors are highly expressed in the renal medulla, the overall aim of this dissertation is to determine the role of Ang II in mediating renal medullary ET s receptor function, and to determine if differences in renal medullary ET 8 receptor function contribute to the sex differences observed in Ang II hypertension. The fust aim was to test the hypothesis that renal medullary ET 8 receptor function is impaired in male Ang II hypertensive rats. However, ET-mediated natriuresis is preserved in female rats in response to chronic Ang II infusion. We compared the diuretic and natriuretic responses to intramedullary infusion of the ET s receptor agonist, sarafotoxin 6c (S6c), in male and female rats treated with.Ang II (260 ng/kg/min s.c.) or vehicle for 14 days. Male Ang II hypertensive rats had impaired ETs-dependent sodium and water excretion. In contrast, renal medullary ET 8 receptor function was preserved in female Ang II-treated rats. Moreover, ETA-mediated diuretic and natriuretic responses were maintained in female Ang II hypertensive rats. These data demonstrate that, in contrast to male Ang II hypertensive rats, ET receptor-induced diuretic and natriuretic responses are preserved in female rats during chronic Ang II infusion. The second aim was to determine ifETs receptors limit the hypertensive response and renal injury induced by chronic Ang II infusion in female rats compared to males. Male and female rats received Ang II infusion (150 ng/kg/min; sc.) along with a high salt diet (4% Na) for 4 weeks; blood pressure was measured by telemetry. After one week of Ang II infusion with a high salt diet, subsets of both male and female rats received the ET8 antagonist, A-192621, at three doses on consecutive weeks (1, 3, and 10 mg/kg/d in food). Male rats had significantly higher blood pressure compared to females after 4 weeks of Ang II. A-192621 resulted in a dose-dependent increase in blood pressure in female Ang II hypertensive rat while there was no significant change in males. After 4 weeks of Ang II infusion, the levels of proteinuria and nephrinuria were higher in male rats compared to female. A-192621 did not further increase urinary excretion of protein or nephrin in either male or female Ang II hypertensive rats. In conclusion, ET 8 receptors provide more protection against hypertension during chronic Ang II infusion in female rats compared to male. The third aim was to determine the physiological role of Ang II in regulating renal ETa receptor function during salt deprivation, a model with high levels of endogenous Ang II. After 2 weeks of normal (0.4% Na) or low (0.01-0.02% Na) salt feeding, the activation of ET B receptors in the renal medulla increased urine flow and sodium excretion of rats on normal salt diet. While urinary ET-1 excretion was comparable between a normal and low salt diet, ET B-dependent diuresis and natriuresis in response to acute intramedullary infusion of S6c was reduced in the low salt treated rats. Chronic treatment with the A Tl receptor antagonist, candesartan, restored ET B-induced water and sodium excretion in rats fed low salt diet. These findings support the hypothesis that A Tl receptors regulate renal medullary ET 8 receptor function in a low salt diet model to conserve sodium. From these studies, we conclude that Ang II"via the A Tl receptor attenuates renal medullary ET 8 receptor function resulting in sodium and water retention. During pathological situations, Ang II has a greater inhibitory effect on ET B receptor function in male rats compared to females, leading to a greater increase in blood pressure in response to chronic Ang II infusion.

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