CIP4 and Src in Promoting the Migration and Invasion of Breast Cancers

Cellular invasion represents a critical early step in the metastatic cascade, and many proteins have been identified as part of an “invasive signature.” The non-receptor tyrosine kinase Src is commonly upregulated in breast cancers, often in conjunction with overexpression of EGFR. Signaling from this pathway stimulates cell proliferation, migration, and invasion and frequently involves proteins that regulate the cytoskeleton. My data demonstrates that inhibition of Src, using the small-molecule inhibitor dasatinib, impairs cellular migration and invasion. Furthermore, Src inhibition sensitizes the cells to the effects of the chemotherapeutic doxorubicin resulting in dramatic, synergistic inhibition of proliferation with combination treatments. The Src-targeted protein CIP4 (Cdc42-interacting protein 4) associates with curved plasma membranes to scaffold complexes of Cdc42 and N-WASp. In these experiments, I show that CIP4 overexpression correlates with triple-negative biomarker status, cellular migration, and invasion of (breast cancer cells. Inhibition of CIP4 expression significantly decreases migration and invasion. Furthermore, I demonstrate the novel finding that CIP4 localizes to invadopodia, which are finger-like projections of the actin cytoskeleton that are associated with matrix degradation and cellular invasion. Depletion of CIP4 in invasive cells impairs the formation of invadopodia and the degradation of gelatin. Therefore, CIP4 is a critical component of the invasive phenotype acquired by human breast cancer cells. In this body of work, I propose a model in which CIP4 promotes actin polymerization by stabilizing the active conformation of N-WASp. CIP4 and N-WASp are both phosphorylated by Src, implicating this pathway in Src-dependent cytoskeletal rearragement. This represents a novel role for F-BAR proteins in migration and invasion.

A study of nurses' judgement of and participation in decision-making for nursing home placement for the elderly

This study investigated the effects of patient variables (physical and cognitive disability, significant others' preference and social support) on nurses' nursing home placement decision-making and explored nurses' participation in the decision-making process.^ The study was conducted in a hospital in Texas. A sample of registered nurses on units that refer patients for nursing home placement were asked to review a series of vignettes describing elderly patients that differed in terms of the study variables and indicate the extent to which they agreed with nursing home placement on a five-point Likert scale. The vignettes were judged to have good content validity by a group of five colleagues (expert consultants) and test-retest reliability based on the Pearson correlation coefficient was satisfactory (average of.75) across all vignettes.^ The study tested the following hypotheses: Nurses have more of a propensity to recommend placement when (1) patients have severe physical disabilities; (2) patients have severe cognitive disabilities; (3) it is the significant others' preference; and (4) patients have no social support nor alternative services. Other hypotheses were that (5) a nurse's characteristics and extent of participation will not have a significant effect on their placement decision; and (6) a patient's social support is the most important, single factor, and the combination of factors of severe physical and cognitive disability, significant others' preference, and no social support nor alternative services will be the most important set of predictors of a nurse's placement decision.^ Analysis of Variance (ANOVA) was used to analyze the relationships implied in the hypothesis. A series of one-way ANOVA (bivariate analyses) of the main effects supported hypotheses one-five.^ Overall, the n-way ANOVA (multivariate analyses) of the main effects confirmed that social support was the most important single factor controlling for other variables. The 4-way interaction model confirmed that the most predictive combination of patient characteristics were severe physical and cognitive disability, no social support and the significant others did not desire placement. These analyses provided an understanding of the importance of the influence of specific patient variables on nurses' recommendations regarding placement. ^

Examination of the influence of behavioral, normative and control beliefs on the adherence to a prescribed renal diet among elderly populations with chronic to end-stage renal disease

The 1999-2004 prevalence of chronic kidney disease in adults 20 year or older (15.5 million) is an estimated 7.69%. The risk of developing CKD is exacerbated by diabetes, hypertension and/or a family history of kidney disease. African Americans, Hispanics, Pacific Islanders, Native Americans, and the elderly are more susceptible to higher incidence of CKD. The challenges of aging coupled with co-morbidities such as kidney disease raises the potential for malnutrition among elderly (for the purpose of this study 55 years or older) populations. Lack of adherence to prescribed nutrition guidelines specific to renal failure jeopardizes body homeostasis and increases the likelihood of future morbidity and resultant mortality. The relationship and synergy that exists between diet and disease is evident. Clinical experience with renal patients has indicated the importance of adherence to diet therapy specific to kidney disease. Extension investigation of diet adherence among endstage renal disease patients revealed a sizeable dearth in the current literature. This thesis study was undertaken to help reduce that void. The study design is qualitative and descriptive. Support, cooperation, and collaboration were provided by the University of Texas Nephrology Department, University of Texas Physicians, and DaVita Dialysis Centers. Approximately 105 male and female chronic to end-stage kidney disease patients were approached to participate in elicitation interviews in dialysis treatment facilities regarding their present diet beliefs and practices. Eighty-five were recruited and agreed to participate. Inclusion criteria required individuals to be between 35-90 years of age; capable of completing a 5-10 minute interview; and English speaking. Each kidney patient was asked seven (7) non-leading questions developed from the constructs of the Theory of Planned Behavior. The study presents a descriptive comparison of behavioral, normative, and control beliefs that influence adherence to renal diets by age, race, and gender. The study successfully concluded that behavioral, normative, and control beliefs of chronic to end-stage renal patients promoted execution and adherence to prescribed nutrition. This study provides valuable information for dietitians, technicians, nurses, and physicians to assess patient compliance toward prescribed nutrition and the means to support or improve that performance. ^

An evaluation of the personal response system program for the elderly in Harris County, Texas

The Personal Response System Program at Huffington Center on Aging, Baylor College of Medicine, provides emergency call systems for elderly people living independently in Houston, Texas. The goal of the project was to complete a formative evaluation of the Personal Response System Program. The specific aims of the evaluation were three-fold. One aim was to evaluate participant health status and level of disability. The second aim was to develop a health care cost estimation strategy. Finally, a preliminary cost-effectiveness analysis was completed to evaluate the program's impact on health care costs and health status among the elderly target population. ^ The evaluation was a longitudinal, randomized experimental design. After the screening of 120 volunteers for eligibility, clients were asked to complete a written questionnaire and a monthly health service contact diary. Volunteers were contacted by telephone interviewers to collect health status information from 100 eligible clients (83%) on three occasions during the six months of follow-up. ^ Initially, volunteers were randomized to two experimental groups. The two groups were found to be comparable at the beginning of the study. No significant differences were detected related to health status, level of disability, or history of physician visits at baseline. However, the group with the Personal Response System (PRS) device had more adverse health events, higher IADL scores, more frequent use of walkers, lower average health status scores, and fewer community volunteers hours than the usual care comparison group. ^ The health care costs were estimated based on an algorithm adapted from the American Medical Association guidelines. Average total health care costs for the group with the PRS device ($912) were greater than the usual care group ($464). However, median health care values for the PRS group ($263) were similar to the usual care comparison group ($234). The preliminary findings indicated that the use of the PRS device was not associated with health care cost savings. ^ In the preliminary cost-effectiveness analysis, use of the personal response system was found to be associated with increased mental health status among elderly clients. The cost-effectiveness evaluation indicated that the associated cost for six months was $710 per unit increase in mental component score when the $150 PRS subscription was included. However, clients with the PRS device were found to have a greater decline in physical health status during the six-month follow-up. The beneficial effect on mental health status was found to be in contrast to negative findings associated with changes in physical health status. The implications for future research relate to the need to identify risk factors among geriatric populations to better target groups that would most likely benefit from PRS Program enrollment. ^

Attributing inpatient care to diabetes: The case of Medicare for the elderly in Texas, 1995

Specific aims. This study estimated the accuracy of alternative numerator methods for attributing health care utilization and associated costs to diabetes by comparing findings from those methods with findings from a benchmark denominator method. ^ Methods. Using Medicare's 1995 inpatient and enrollment databases for the elderly in Texas, the researcher developed alternative estimates of costs attributable to diabetes. Among alternative numerator methods were selection of all records having diabetes as a principal or secondary diagnosis, and a complex ICD-9-CM sorting routine as previously developed for study of diabetes costs in Texas. Findings from numerator methods were compared with those from a benchmark denominator method based on attributable risk and adapted from a study of national diabetes costs by the American Diabetes Association. This study applied age, gender and ethnicity specific estimates of diabetes prevalence taken from the 1987–94 National Health Interview Surveys to person-months of Medicare Part A, non-HMO enrollment for Texas in 1995. Outcome measures were number of persons identified as having diabetes using alternative definitions of the disease; and number of hospital stays, patient days, and costs using alternative methods for attributing care and costs to diabetes. Cost estimates were based on Medicare payments plus deductibles, co-pays and third party payments. ^ Findings. Numerator methods for attributing costs to diabetes produced findings quite different than those from the benchmark denominator method. When attribution was based on diabetes as principal or secondary diagnosis, the resulting estimates were significantly higher than those obtained from the denominator method. The more complex sorting routine produced estimates near the lower boundary for the confidence interval associated with estimates from the benchmark method. ^ Conclusions. Numerator methods employed by previous researchers poorly estimate the costs of diabetes. While crude mathematical adjustment can be made to the respective numerator approaches, a more useful strategy would be to refine the complex sorting routine to include more hospitalizations. This report recommends approaches to improving methods previously employed in study of diabetes costs. ^

The in vivo and in vitro formation of sticky DNA and the GAA.TTC trinucleotide repeat associated with Friedreich's ataxia

Friedreich's ataxia is caused by the expansion of the GAA•TTC trinucleotide repeat sequence located in intron 1 of the frataxin gene. The long GAA•TTC repeats are known to form several non-B DNA structures including hairpins, triplexes, parallel DNA and sticky DNA. Therefore it is believed that alternative DNA structures play a role in the loss of mRNA transcript and functional frataxin protein in FRDA patients. We wanted to further elucidate the characteristics for formation and stability of sticky DNA by evaluating the structure in a plasmid based system in vitro and in vivo in Escherichia coli. The negative supercoil density of plasmids harboring different lengths of GAA•TTC repeats, as well as either one or two repeat tracts were studied in E. coli to determine if plasmids containing two long tracts (≥60 repeats) in a direct repeat orientation would have a different topological effect in vivo compared to plasmids that harbored only one GAA•TTC tract or two tracts of < 60 repeats. The experiments revealed that, in fact, sticky DNA forming plasmids had a lower average negative supercoil density (-σ) compared to all other control plasmids used that had the potential to form other non-B DNA structures such as triplexes or Z-DNA. Also, the requirements for in vitro dissociation and reconstitution of the DNA•DNA associated region of sticky DNA were evaluated. Results conclude that the two repeat tracts associate in the presence of negative supercoiling and MgCl 2 or MnCl2 in a time and concentration-dependent manner. Interaction of the repeat sequences was not observed in the absence of negative supercoiling and/or MgCl2 or in the presence of other monovalent or divalent cations, indicating that supercoiling and quite specific cations are needed for the association of sticky DNA. These are the first experiments studying a more specific role of supercoiling and cation influence on this DNA conformation. To support our model of the topological effects of sticky DNA in plasmids, changes in sticky DNA band migration was measured with reference to the linear DNA after treatment with increasing concentrations of ethidium bromide (EtBr). The presence of independent negative supercoil domains was confirmed by this method and found to be segregated by the DNA-DNA associated region. Sequence-specific polyamide molecules were used to test the effect of binding of the ligands to the GAA•TTC repeats on the inhibition of sticky DNA. The destabilization of the sticky DNA conformation in vitro through this binding of the polyamides demonstrated the first conceptual therapeutic approach for the treatment of FRDA at the DNA molecular level. ^ Thus, examining the properties of sticky DNA formed by these long repeat tracts is important in the elucidation of the possible role of sticky DNA in Friedreich's ataxia. ^

Characterization of the interactions between fibronectin and the Borrelia burgdorferi lipoprotein, BBK32

The findings presented in this dissertation detail the complex interaction between BBK32 and fibronectin and describe novel consequences of the interaction. BBK32 is a fibronectin-binding protein on Borrelia burgdorferi, the causative agent of Lyme disease. We found that BBK32 contains multiple fibronectin-binding motifs, recognizing the fibronectin N-terminal domain (NTD) and the gelatin binding domain (GBD) in an anti-parallel order, where corresponding sites in BBK32 and fibronectin are aligned so that there is a one-to-one interaction between the proteins. While characterizing this interaction, we discovered that binding of BBK32 to the GBD inhibits the migration stimulating factor's (MSF) motogenic activity. In the presence of BBK32, endothelial cells do not migrate in response to increasing concentrations of MSF or the GBD. MSF is found under wound healing conditions, and inhibition of its activity may allow the tick-transmitted spirochetes to delay wound healing and to establish an infection. ^ Biophysical structural studies, designed to identify a mechanism of interaction, revealed that BBK32 binding to the NTD leads to the unfolding of plasma fibronectin, which exposes α5β1 integrin recognition motifs. Binding assays demonstrate that the BBK32-NTD interaction enhances the plasma fibronectin-α5β1 integrin interaction, which may allow B. burgdorferi to invade host cells, and thereby evade the host immune system. ^ We also determined that BBK32 binds fibronectin F3 modules, which leads to plasma fibronectin aggregation and induction of superfibronectin. The resulting superfibronectin is conformationally distinct from plasma and cellular fibronectin, and can inhibit endothelial cell proliferation. BBK32's active superfibronectin-forming motif has been located to a region between residues 160 and 175, which contains two sequence motifs that are also found in anastellin, the only other known superfibronectin-inducing protein. ^ A potential consequence of BBK32-induced superfibronectin formation was identified. BBK32-induced superfibronectin formation results in the exposure of α4β1 integrin recognition sequences in fibronectin. The α4β1 integrin is required for leukocyte transendothelial cell migration. BBK32-induced superfibronectin inhibits this activity. The inhibition of leukocyte recruitment to the infection site may slow the activity of the host immune system, and permit the spirochetes to establish an infection. ^

Integrated pest management in multi-story public housing for the elderly in Houston, Texas

Integrated pest management is a viable alternative to traditional pest control methods. A paired sample design was utilized to measure the effect of IPM education on the number of cockroaches in a 200 unit, seven story public housing building for the elderly in Houston, TX. Glue traps were placed in 71 randomly selected apartments (5traps/unit) and left in place for two nights. Baseline cockroach counts were shared with the property manager, maintenance/janitorial staff, service coordinator, pest control professional and tenant representatives at the end of a one day “Integrated Pest Management in Multi-Family Housing” training course.^ There was a significant decrease in the average number of cockroaches after IPM education and implementation of IPM principles (P < 0.0003). Positive changes in behavior by members of the IPM team and changes in the housing authority operational plan were also found. Paired t-tests comparing the difference between mean cockroach counts at baseline and follow-up by location within the apartment all demonstrated a significant decrease in the number of cockroaches.^ Results supported the premise that IPM education and the implementation of IPM principles are effective measures to change pest control behaviors and control cockroaches. Cockroach infestations in multi-story housing are not solely determined by the actions of individual tenants. The actions of other residents, property managers and pest control professionals are also important factors in pest control.^ Findings support the implementation of IPM education and the adoption of IPM practices by public housing authorities. This study adds to existing evidence that clear communication of policies, a team approach and a commitment to ongoing inspection and monitoring of pests combined with corrective action to eliminate food, water and harborage and the judicial use of low risk pesticides have the potential to improve the living conditions of elderly residents living in public housing.^

Utilization behavior of the elderly in an HMO: A causal analysis

Planning and providing health care services for the elderly represents a major challenge to the health care system. One part of that challenge is the identification of those factors which determine the utilization of services by this population. The purpose of this study is to explain the use of health care services by elderly subscribers in a prepaid group health plan, using the theoretical framework developed by Andersen and Aday. The impact of the predisposing, enabling and need factors on utilization was modelled through a structural equation approach using LISREL. The data were derived from Kaiser-Permanente's Medicare Prospective Payment Project, August 1980-December 1982. Need factors, in general, were the most significant determinants of utilization, with the predisposing and enabling factors found to be secondary but necessary links in the causal chain. The model was fitted to the data from the youngest age group (65-74 years) and then evaluated for goodness of fit in the two older groups (75-84 and 85+ years). Implications of the study's findings and suggestions for further modelling the utilization behavior of the elderly are discussed. ^