▼ Because of insufficient self-repair, recovery from spinal cord injury (SCI) is limited. The neurotrophin brain-derived neurotrophic factor (BDNF) shows promise for SCI treatment, although significant barriers to delivery have been identified. Therefore, the effects of pegylated BDNF (peg-BDNF, a pharmacologically modified BDNF protein) on repair and recovery were examined after experimental rat SCI. Morphological analysis revealed significantly improved delivery of peg-BDNF compared to unmodified BDNF. However, peg-BDNF did not improve anatomical or functional responses observed with unmodified BDNF. Both interventions stimulated accelerated locomotor recovery and hindlimb airstepping (a spontaneous locomotor movement). Similarly, neither treatment induced tissue sparing or axon regeneration, although both provoked sprouting in cholinergic axons. Of the factors potentially limiting BDNF's effects, the paucity of tissue within the lesion is a fundamental problem that may limit repair, since studies suggest promising effects of intralesion tissue transplantation. Recently, marrow stromal cells (MSCs-stem cells found in adult bone marrow) have been considered for such transplantation. To examine the effects of MSC transplants and explore the idea that BDNF's actions are limited by the paucity of growth-supportive tissue, rats received SCI and intraspinal transplantation of cultured MSCs with or without peg-BDNF co-infusion. Stereological analysis revealed that MSCs were well-tolerated, partially filling the cavities normally observed after SCI. Furthermore, MSCs provoked tissue and myelin sparing and supported properly oriented axon regeneration, demonstrating protective and reparative actions. Additionally, MSCs stimulated spontaneous airstepping, suggesting locomotor activation. Although BDNF / MSC co-treatment did not improve functional recovery, axon regeneration was significantly enhanced, compared to MSC transplantation alone. The protective effects of MSCs, however, were negated by BDNF co-infusion, demonstrating that more progress is needed before this combinatorial intervention could be applied to patients. Thus, BDNF delivery alone is not sufficient to stimulate functional recovery or significant repair after SCI. However, when delivered in the presence of a regeneration-supportive matrix, BDNF effectively stimulates regeneration. Additionally, MSCs may be an attractive source of transplant tissue for SCI intervention, since the transplants are tissue protective, enhance regeneration, and stimulate locomotor activities. Thus, these studies should aid in developing future strategies aimed at improving SCI outcomes. Advisors/Committee Members: Stokes, Bradford T.

Advisors/Committee Members: Hill, Richard M.

▼ The activity-dependent plasticity is the foundation for normal spinal function. When spinal cord injury (SCI) interrupts the pathways of the spinal circuitry, normal input is altered, and pathological plasticity and abnormal reflexes develop. Thus, it becomes necessary to re-connect the interrupted spinal cord reflex pathways, and also to reshape or re-educate these pathways, to restore even partial function. Operant conditioning of the spinal stretch reflex (SSR) or its electrical analog, the H-reflex, provides a new method to induce long-term plasticity within the spinal cord. In response to an operant conditioning protocol, primates and rodents can gradually increase or decrease the reflex. The conditioning changes the spinal cord and appears to be dependent only on the corticospinal tract. The goal of this study was to determine whether H-reflex conditioning could help to modulate and guide normal functional recovery after SCI. The hypotheses were: (1) that up-conditioning of H-reflex will increase and down-conditioning will decrease the reflex during locomotion; (2) that H-reflex conditioning can reduce asymmetry in locomotion after SCI and that appropriate reflex conditioning can improve locomotion and restore function. These hypotheses were tested by studying soleus muscle activity during locomotion in normal rats and in rats with a lateral column (LC) transection before and after H-reflex conditioning. Results indicate that: 1) in normal rats in which the soleus H-reflex had been decreased by down-conditioning, the H-reflexes elicited during locomotion were also smaller. Similarly, the locomotor H-reflexes were larger in up-conditioned rats. However, the conditioning-induced changes did not affect the duration, length, or right/left symmetry of the step cycle. 2) in rats with LC transection in which a persistent asymmetry in treadmill locomotion was evident, up-conditioning increased the H-reflex and ameliorated the locomotor asymmetry. This improvement was accompanied by a significant increase in right soleus burst amplitude. In contrast, in LC rats without up-conditioning exposure, the locomotor asymmetry persisted and no other significant changes occurred. These results suggest that H-reflex conditioning may be able to reduce the functional deficits associated with SCI. In combination with other therapeutic methods, appropriate reflex conditioning may be able to maximize restoration of function after SCI. Advisors/Committee Members: Jakeman, Lyn B.

Advisors/Committee Members: Hakel, Milton D.

▼ Background and Aims: The general aim was to elucidate the role of cAMP signaling in intact neural circuits of the enteric nervous system in normal or inflamed gut. Forskolin binding, AC-ir and FIChR/cAMP recordings suggest AC/cAMP signaling occurs in a heterogeneous population of gut neurons. An acrolein-derivatized cAMP antiserum was developed and used for the visualization, quantitation, classification and polarity of gut neurons. We tested hypothesis 1 that cAMP signaling occurs in functional classes of neurons other than AH/Dogiel Type II intrinsic primary afferent neurons (IPANs). Hypothesis 2 tested if cAMP signaling in the two neural plexuses contributes to cAMP-dependent reflexes. Hypothesis 3 tested if amplification of the R/Gs/AC/cAMP-dependent pathway occurs in intestinal inflammation induced by Trichinella spiralis infection. Experimental Design: Forskolin stimulation was used for visualization of cAMP immunoreactivity, quantitation and functional classification of neurons according to their morphology and polarity. This technique was complimented by physiological, electrophysiological, molecular, immunochemical, ELISA or biochemical approaches in normal or T. spiralis infected jejunum. Results: Overall, 15-20% of myenteric and 60% of submucous neurons generate cAMP. Myenteric cAMP-visualized neurons had polarized projections for descending reflexes. Visualized cells were classified as IPANs with Dogiel II shape, descending myenteric interneurons (Dogiel I/filamentous), descending LM motor neurons (Dogiel I/simple), short-projection interneurons (Dogiel I/lamellar), VIP-ergic secretomotor neurons (filamentous), novel Dogiel I/lamellar or simple submucous neurons. Co-localization occurred with cAMPir in VIP but not NPY – secretomotor-neurons. Notable differences between the plexuses exist in cAMP/cGMP cross-talk, PDE IV activity, A1/A2aR cAMP coupling, polarity, proportions and numbers of each type. Synaptic blockade or neurosecretion studies indicated that cAMP contributes to synaptic communication. Acute inflammation causes AH cell hyper-excitability, elevates AC expression in calbindin-D28 and calretinin-positive neurons and amplification in ganglionic cAMP content in response to various stimulants. Inflammation, histamine or forskolin also induce phosphorylation of CREB that is blocked by cAMP-dependent PKA inhibition. H1/H2 histamine or COX 2 inhibitors attenuate AH hyper-excitability. Conclusion. The cAMP antiserum provided new insights into cAMP function in the enteric nervous system. Cyclic AMP signaling is involved in specific neural circuits, polysynaptic pathways, neurosecretion, motility reflexes, neuronal hyperexcitability in inflamed gut and neuronal plasticity. Advisors/Committee Members: Christofi, Fievos L.

▼ Electric stimulation of interganglionic fiber tracts in the submucosal plexus of guinea-pig small intestine evoked synaptic responses that included slow excitatory postsynaptic potentials (slow EPSPs). The submucosal slow EPSPs were subdivided into three categories consisting of “pure-purinergic”, “partial-purinergic” and “non-purinergic” according to their sensitivity to a specific P2Y1 receptor antagonist, MRS2179 (10 µM). Most of the purinergic slow EPSPs were found in submucosal secretomotor neurons associated with stimulus-evoked slow IPSPs, which were known electrophysiological markers for VIPergic secretomotor neurons. Application of known purinergic agonists including ATP, 2-methio-ATP etc evoked slow EPSP-like responses in the submucosal neurons with a potency order consistent with that of P2Y1 receptors in other systems. The excitatory action of ATP was suppressed by MRS2179 in a competitive manner. Pharmacological analysis suggested that the phospholipase C → IP3 → calmodulin kinase / protein kinase C post receptor signal transduction cascade mediated the purinergic P2Y1 receptor-evoked depolarizing responses in submucosal secretomotor neurons. Neurons that supplied P2Y1 purinergic slow excitatory synaptic input to the secretomotor neurons in the submucosal plexus were found in the myenteric and submucosal plexuses and in prevertebral sympathetic ganglia. Full-length guinea-pig P2Y1 receptor cDNA cloned from the submucosal plexus was used to transfect HEK293 cells. ATP or its analogs induced intracellular calcium release in transfected HEK293 cells, which was suppressed by MRS2179. ATP evoked neurogenic mucosal secretion by activating the P2Y1 receptor in guinea-pig small intestine. The presence of MRS2179 in the Ussing chambers also suppressed the secretory responses evoked by electrical field stimulation. The results of the project provide for the first evidence for establishing ATP as a neurotransmitter for slow synaptic excitation in the submucosal plexus of guinea-pig small intestine. The signal transduction pathway for purinergic slow synaptic excitation includes activation of phospholipase C and intracellular IP3 receptors. Protein kinase C and Calmodulin-dependent protein kinases are also involved. Ussing chamber experiment revealed the role of the P2Y1 receptor in neurogenic mucosal secretion into the gut lumen. Identification of the functional purinergic component of enteric neurotransmission provides a basis for therapeutic drug development by targeting the P2Y1 receptor and purine metabolic pathways. Advisors/Committee Members: Wood, Jackie D.

▼ Previous research suggests that humor has beneficial effects on mood, health status, and pulmonary functioning among healthy adults. However, no previous studies have examined the effects of humor among individuals with chronic obstructive pulmonary disease (COPD), despite the fact that patients with COPD are at risk for impairments in emotional well-being, quality of life, pulmonary functioning, and health status. Two studies were conducted to evaluate the effect of humor among patients with COPD. Study 1 was an acute humor intervention in which participants viewed either a Humorous or Neutral video presentation. Participants were evaluated with pulmonary function tests, heart rate and blood pressure monitoring, and questionnaires assessing affect and state anxiety both before and after the video intervention. The sample included 22 participants (36% male) with a mean age of 67.8 (±8.8) years who exhibited severe airway obstruction [mean forced expiratory volume in 1 second/forced vital capacity ratio (FEV1/FVC)=0.52(±.17)]. Results indicated that functional residual capacity increased in the Humor participants (mean change=0.9 liters, p<.05), but decreased among the Neutral participants (mean change=-0.2 liters, p<.02). In addition, Humor participants exhibited a trend toward increased residual volume. Disease severity predicted change in air trapping following the humor intervention, with increased air trapping exhibited by those with less severe pulmonary disease. Study 2 examined the psychological and health benefits associated with a sense of humor and the use of humor as a coping style among individuals with COPD. The sample included 46 participants (41% male) with a mean age of 66.9(±9.9) who completed one comprehensive assessment of humor, depression, trait anxiety, affect, quality of life, and recent infectious illnesses. Correlational analyses revealed that a humorous coping style was associated with decreased depression (r=-.47, p<.001), diminished anxiety (r=-.51, p<.001), decreased negative affect (r=-.32, p <.04), improved positive affect (r=.46, p<.01), enhanced quality of life (r=.57, p<.001), and fewer days with an infectious illness (r=-.34, p<.02). Sense of humor was correlated with decreased anxiety (r=-.39, p<.01) and improved positive affect (r=.35, p<.02). These studies offer preliminary evidence that individuals with COPD may reap psychological and health benefits from having humorous personality attributes, particularly a humorous coping style. However, laughing aloud may cause acute decreases in pulmonary functioning by increasing the amount of trapped air in the lungs. Advisors/Committee Members: Emery, Charles F.

▼ A series of seven studies converge in demonstrating that controlled discriminatory behavior can often occur outside of conscious awareness or intent. Results indicate that the racial group membership of criminal defendants in a criminal sentencing paradigm had a strong impact on retributive outcomes, with Hispanic defendants receiving significantly harsher sentences than White defendants for the identical crime. The studies described in Chapter 1 sought to ascertain the existence of discriminatory bias in criminal sentencing, and to demonstrate that such bias is unintentional. It was demonstrated that discrimination was unrelated to individual differences in prejudice (Experiment 1) and stereotyping (Experiment 2), as well as participants' self-perceptions of discrimination (Experiments 1 and 2). Chapter 2 reports studies designed to rule out certain methodological and demand alternative explanation for the findings of Chapter 1. Experiment 3 showed that discriminatory bias occurs even under high accountability conditions while Experiment 4 ruled out the possibility that bias arose due to a flawed dependent variable. Finally, Chapter 3 explores the extent to which the bias is correctable and also explores underlying antecedents of the effect. Overall, results of these experiments provide compelling evidence that discrimination may occur without awareness or intention, even when perceivers have complete control over their actions. Advisors/Committee Members: Brewer, Marilynn.

▼ The Na+/I- symporter (NIS) is a membrane protein mediating iodide uptake in thyrocytes. It can be upregulated by thyrotropin and facilitates 131I uptake in differentiated thyroid cancers (DTC) to ablate the tumors. Therefore, it has been proposed that NIS expression in surgical samples may serve as a predictor for effectiveness of 131I therapy in DTC. However, its predictive value can be compromised by the difference in serum thyrotropin levels between when surgical samples are obtained and when radioactive iodine uptake (RAIU) is measured. To address this issue, we performed ex vivo thyrotropin-stimulated tissue culture from surgical samples and found that thyrotropin-stimulated NIS mRNA expression showed a better correlation with thyrotropin-induced RAIU, as compared to NIS mRNA expression in surgical samples. Thus, thyrotropin-stimulated NIS expression may be a useful predictor of thyrotropin-induced RAIU in thyroid cancers. Non-thyroid malignancies can also benefit from NIS-mediated radionuclide therapy, provided that NIS can be expressed and functioning in the tumors. We demonstrated exogenous NIS-mediated RAIU in tumors by imaging of the intracerebral NIS-expressing gliomas and by ex vivo tissue counting. A significant difference of RAIU in tumors versus in normal tissues was noted. Despite a short radioiodine retention-time in NIS-expressing gliomas, 131I treatment was able to enhance the survival of rats carrying NIS-expressing gliomas. The therapeutic efficacy of 131I is dose-dependent and intervention time-dependent. The therapeutic effectiveness was further supported by the finding that life spans of 131I-treated rats bearing NIS-expressing gliomas was inversely related to the remaining NIS-expressing cells in tumors. Finally, we investigated the usefulness of 125I and 188ReO4 in treating rats bearing NIS-transduced gliomas. Both 188ReO4 and combined 131I/125I therapy were more effective than 131I alone in prolonging survival time of rats carrying NIS-transduced gliomas. In conclusion, ex vivo TSH-stimulated NIS expression is useful to predict TSH-induced RAIU in thyroid cancers. For non-thyroid cancers, NIS gene transfer renders the tumor sensitive to 131I treatment. The therapeutic effectiveness of NIS-mediated radionuclide therapy can be further optimized by adjustment of intervention time and the use of alternative NIS substrates with potent irradiation. Advisors/Committee Members: Jhiang, Sissy M.

Advisors/Committee Members: Wickens, Delos.

▼ Despite the serious nature and growing magnitude of female juvenile delinquency, the existing body of research on adolescent female offenders is very limited when compared to the study of delinquent activity among males. Because previous research documents gender differences in the nature and etiology of juvenile delinquency (Chesney-Lind & Sheldon, 1992; Henggeler, Edwards, & Borduin, 1987), findings from research on male juvenile delinquents may not readily contribute to our understanding of delinquent behavior among females. Consequently, the aim of the project was to explore the concomitants or the psychological contexts of adolescent female offenders as well as those factors that contribute to their delinquent activity.Specifically, this study explored aspects of the psychological functioning and family contexts of female juvenile offenders. The sample consisted of 75 adolescents who were incarcerated in a juvenile correctional facility; of the parents who consented for their daughter to participate in the study, 48 also took part.Regarding the adolescents' psychological functioning, results indicated that female delinquents exhibit numerous emotional and behavioral problems. These included both externalizing behaviors, such as conduct disorder and oppositional

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