The influence of ideological interest groups on congressional financial support of international family planning

The World Health Organization estimates there are about 585,000 maternal deaths each year, with 98% of the maternal deaths in developing countries. Access to family planning methods is one method to decrease maternal mortality and morbidity. ^ The U.S. was the leader in providing financial and technical assistance to developing countries to enable women to have this access. The election of Ronald Regan changed the course of U.S. support; abortion became a central factor in the political decision-making with regards to the financial support of international family planning. ^ One factor that may sway policy-makers' decisions is the influence of ideological interest groups, Political Action Committees funding of candidates in relation to votes on bills that impacted on financial support of international family planning and the amount spent by these groups on lobbyist was reviewed. Pro-choice funding of candidates was greater for the four of the fives votes supporting family planning. Pro-Choice lobbyist spending was $185,000 vs. $8,184,000 spent by Pro-Life ideological groups. ^

The role of AT1 receptor autoantibodies in the pathophysiology of preeclampsia

Preeclampsia is a disease that affects 3–5% of all pregnancies. The cause is unknown and there is currently no treatment. The disease poses significant health risks to both the mother and the fetus. To date, research on the topic has not produced a convincing cause for the development of the hallmark symptoms of preeclampsia. The hypothesis of an agonistic autoimmune response to the AT1 receptor is presented. Immunoglobulin fractions from normotensive and preeclampsia patients were prepared for experimental tests. Model systems were tested in three categories to determine if AT 1 receptor specific activation and receptor-ligand interaction was caused by a suspected autoantibody. Activation was found in rat neonatal cardiornyocytes that caused an increased contraction rate. This activity was found in preeclampsia patients, absent in normotensive patients. The activation was antagonized by losartan, an AT1 receptor antagonist, and by epitope peptide competition of the receptor-ligand type interaction. This epitope was the 7 amino acid peptide fragment, AFHYESQ, a sequence present in the second extracellular loop of the AT1 receptor. The patterns of AT1 receptor activation were also found in a human trophoblast cell line, HTR8, with an effect on Pai-1 secretion, a factor that plays a role in preventing hypercoagulation. In human mesangial cells, the AT1 receptor autoantibody present in the immunoglobulin fraction from preeclampsia patients was found to stimulate the secretion of Pai-1, and IL-6, a factor that plays a role in the activation of an inflammatory response. This activity was found in samples from preeclampsia patients, but absent in normotensive patients. Tests including losartan, AFHYESQ, and a non-competitive peptide demonstrated that the secretion of Pai-1 and IL-6 met the criteria for AT1 receptor activation by the suspected agonistic autoantibody. These three model systems address relevant pathophysiology for preeclampsia patients, including increased cardiac output, abnormal placentation, and renal damage. The AT1 receptor agonistic autoantibody is potentially a key player in the development of the pathology and symptoms of preeclampsia. ^

Activation of dendritic cells from patients with epithelial ovarian cancer

Dendritic cells (DCs) are the most potent antigen-presenting cells for inducing immune responses to tumor cells. Lin−HLA-DR + DC populations in peripheral blood mononuclear cells (PBMCs) and in ascites mononuclear leukocytes (MNLs) of patients with epithelial ovarian cancer (EOC) are phenotypically immature. Lin−HLA-DR + DCs from PBMCs of normal subjects and EOC patients and MNLs from ascites cells of patients were examined for specific cell surface markers or indicators of differentiation or activation. Separating Lin− HLA-DR+ DCs into subsets based on their HLA-DR intensity provided an additional method for identifying the two major lineages of DCs, myeloid and plasmacytoid. The activation potential of these DCs following exposure to the maturation agents CD40 ligand (CD40L) and lipopolysaccharide (LPS) was examined by measurement of IL-12 and IL-10 concentrations in DC culture supernatants in addition to their ability to stimulate allogeneic T cells. DCs from PBMCs of normal subjects and EOC patients and DCs isolated from ascites MNLs of EOC patients were separated into subsets based on CD11c and CD123 cell surface marker expression identifying the major DC types. These subsets were then compared with cells sorted on the basis of HLA-DR intensity. The in vivo behavior of DCs and DC subsets in peripheral blood and ascites following treatment of peritoneal carcinoma patients with the growth factor fins-like tyrosine kinase 3 ligand (Flt3L) was also examined. Increases in proportions and total numbers of DCs from peripheral blood and ascites were associated with increased secretion of IL-12 and IL-10 following in vitro activation of cultured DCs. There were differences between DCs from PBMCs and ascites and between DC subsets in expression of cell surface markers, cytokine profile, and the ability of Lin−HLA-DR + cells to stimulate proliferation of allogeneic T cells from EOC patients. These Lin−HLA-DR+ cells have certain functional properties that suggest that they could have the potential to facilitate an adaptive anti-tumor immune response. ^

Interventions to reduce sexual risk behavior in African American men

The purpose of this review was to describe characteristics of interventions that have been conducted for African American men and identify similarities and differences between interventions for subpopulations of African American men. Of the 473 studies identified through database searching, 8 studies met the eligibility criteria for this review. Target populations within these studies included heterosexual men, homosexual and bisexual men, persons with mental health problems, and injection and non-injection drug users. Little variation was found in the theories and methods used in interventions for different target populations. However, several different behavioral determinants were addressed within these interventions. Although interventions for drug users generally did not exclude individuals based on sexual orientation, these interventions were able to address HIV sexual risk behavior in heterosexual, homosexual, and bisexual-identified men. Given these findings, multi-faceted approaches to HIV prevention are recommended in order to reduce HIV risk in African American men.^

Racial disparities in patient survival after liver transplantation in the United States

Background. Racial disparities in healthcare span such areas as access, outcomes after procedures, and patient satisfaction. Previous work suggested that minorities experience less healthcare and worse survival rates. In adult orthotopic liver transplantation (OLT) mixed results have been reported, with some showing African-American recipients having poor survival compared to Caucasians, and others finding no such discrepancy. ^ Purpose. This study’s purpose was to analyze the most recent United Network for Organ Sharing (UNOS) data, both before and after the implementation of the Model for End-Stage Liver Disease (MELD)/Pediatric End-Stage Liver Disease (PELD) scoring system, to determine if minority racial groups still experience poor outcomes after OLT. ^ Methods. The UNOS dataset for 1992-2001 (Era I) and 2002-2007 (Era II) was used. Patient survival rates for each Era and for adult and pediatric recipients were analyzed with adjustment. A separate multivariate analysis was performed on African-American adult patients in Era II in order to identify unique predictors for poor patient survival. ^ Results. The overall study included 66,118 OLT recipients. The majority were Caucasian (78%), followed by Hispanics (13%) and African-Americans (9%). Hispanic and African-American adults were more likely to be female, have Hepatitis C, to be in the intensive care unit (ICU) or ventilated at time of OLT, to have a MELD score ≥23, to have a lower education level, and to have public insurance when compared to Caucasian adults (all p-values < 0.05). Hispanic and African-American pediatric recipients were more likely have public insurance and less likely to receive a living donor OLT than were Caucasian pediatric OLT recipients (p <0.05). There was no difference in the likelihood of having a PELD score ≥21 among racial groups (p >0.40). African-American adults in Era I and Era II had worse patient survival rates than both Caucasians and Hispanic (pair-wise p-values <0.05). This same disparity was seen for pediatric recipients in Era I, but not in Era II. Multivariate analysis of African-American recipients revealed no unique predictors of patient death. ^ Conclusions. African-American race is still a predictor of poor outcome after adult OLT, even after adjustment for multiple clinical, demographic, and liver disease severity variables. Although African-American and Hispanic subgroups share many characteristics previously thought to increase risk of post-OLT death, only African-American patients have poor survival rates when compared to Caucasians. ^

US medical students' knowledge of obstetric fistula in developing countries

Obstetric fistula is a devastating child birth injury affecting millions of women worldwide. This paper explores the knowledge and understanding of medical students at the University of Texas Health Science Center at San Antonio regarding this global public health issue. Obstetric fistula has been eradicated in most industrialized nations, and has therefore faded from view of many modern medical organizations. The United Nations Population Fund has launched a “Campaign to End Fistula” in an attempt to bring global awareness to this preventable and treatable condition. Based on a survey administered to medical students at UTHSCSA, a baseline understanding of this disorder based on current curriculum is reviewed, with the objective of improving future physicians’ awareness of obstetric fistula. Despite a low survey response rate, there was a significant association between greater knowledge about causes, treatment, and complications of obstetric fistula and advanced years in medical school. However, the fourth year medical students averaged only a 70.5 percent of correct responses on the survey, indicating room for improvement in addressing this topic during medical school. ^

A case-control study to identify risk factors for preterm labor in Colorado Springs, Colorado

The study objectives were to determine risk factors for preterm labor (PTL) in Colorado Springs, CO, with emphasis on altitude and psychosocial factors, and to develop a model that identifies women at high risk for PTL. Three hundred and thirty patients with PTL were matched to 460 control patients without PTL using insurance category as an indirect measure of social class. Data were gathered by patient interview and review of medical records. Seven risk groups were compared: (1) Altitude change and travel; (2) Psychosocial ((a) child, sexual, spouse, alcohol and drug abuse; (b) neuroses and psychoses; (c) serious accidents and injuries; (d) broken home (maternal parental separation); (e) assault (physical and sexual); and (f) stress (emotional, domestic, occupational, financial and general)); (3) demographic; (4) maternal physical condition; (5) Prenatal care; (6) Behavioral risks; and (7) Medical factors. Analysis was by logistic regression. Results demonstrated altitude change before or after conception and travel during pregnancy to be non-significant, even after adjustment for potential confounding variables. Five significant psychosocial risk factors were determined: Maternal sex abuse (p = 0.006), physical assault (p = 0.025), nervous breakdown (p = 0.011), past occupational injury (p = 0.016), and occupational stress (p = 0.028). Considering all seven risk groups in the logistic regression, we chose a logistic model with 11 risk factors. Two risk factors were psychosocial (maternal spouse abuse and past occupational injury), 1 was pertinent to maternal physical condition ($\le$130 lbs. pre-pregnancy weight), 1 to prenatal care ($\le$10 prenatal care visits), 2 pertinent to behavioral risks ($>$15 cigarettes per day and $\le$30 lbs. weight gain) and 5 medical factors (abnormal genital culture, previous PTB, primiparity, vaginal bleeding and vaginal discharge). We conclude that altitude change is not a risk factor for PTL and that selected psychosocial factors are significant risk factors for PTL. ^

A woman's right to know: A policy review of abortion legislation in Texas

Introduction: Despite its legalization, abortion remains a controversial issue, one that has many divided on either side of the political spectrum. While there have been several changes made to abortion policy over the past few decades, one that continues to have many asking questions is the Woman’s Right to Know Act, a piece of state imposed abortion legislation that has implemented strict restrictions and requirements of women seeking abortion, including pre-abortion mandatory counseling and a 24 hour waiting period. This project analyzed four controversial components of the mandatory counseling materials in Texas in an attempt to examine the scientific validity behind this legislation. Methods: In order to understand the scientific validity behind the content of the preabortion mandatory counseling, I conducted a systematic literature review to analyze: the purported link between abortion and breast cancer, the existence of fetal pain, the risk of abortion to future fertility, and the negative psychological effects of abortion. An electronic search in EBSCO and PubMed of review articles published between 1995 and 2010 resulted in fourteen reviews. Results: Results of the systematic review found (1) inconclusive evidence suggesting a link between abortion and breast cancer, (2) that fetal pain likely does not occur until the third trimester of pregnancy, (3) that associations exist between induced abortion and subsequent preterm birth and placenta previa, and (4) that there is mixed evidence relating to the negative psychological effects that exist among women having had an abortion and those who have not had abortion. Conclusion: Based on these conclusions, a recommendation was made to revise the current state mandated counseling materials to reflect more accurate and scientifically-based information about abortion and its potential risks.^

The illness experiences of African Americans residing in an inner city community, Houston, Texas

This dissertation documents health and illness in the context of daily life circumstances and structural conditions faced by African American families living in Clover Heights (pseudonym), an inner city public housing project in the Third Ward, Houston, Texas. Drawing from Kleinman's (1980) model of culturally defined health care systems and using the holistic-content approach to narrative analysis (Lieblich, Tuval- Mashiach, & Zilber, 1998) the purpose of this research was to explore the ways in which social and health policy, economic mobility, the inner city environment, and cultural beliefs intertwined with African American families' health related ideas, behaviors, and practices. I recruited six families using a convenience sampling method (Schensul, Schensul, & LeCompte, 1999) and followed them for fourteen months (2010–2011). Family was defined as a household unit, or those living in the same residence, short or long-term. Single, African American women ranging in age from 29–80 years headed all families. All but one family included children or grandchildren 18 years of age and younger, or children or other relative 18 years of age and older. I also recruited six residents with who I became acquainted over the course of the project. I collected data using traditional ethnographic methods including participant-observation, archive review, field notes, mapping, free-listing, in-depth interviews, and life history interviews. ^ Doing ethnography afforded the families who participated in this project the freedom to construct their own experiences of health and illness. My role centered on listening to, learning from, and interpreting participants' narratives, exploring similarities and differences within and across families' experiences. As the research progressed, a pattern concerning diagnosis and pharmacotherapy for children's behavioral and emotional problems, particularly attention-deficit hyperactivity disorder (ADHD) and pediatric bipolar disorder (PBD), emerged from my formal interactions with participants and my informal interactions with residents. The findings presented in this dissertation document this pattern, focusing on how mothers and families interpreted, organized, and ascribed meaning to their experiences of ADHD and PBD. ^ In the first manuscript presented here, I documented three mothers' narrative constructions of a child's diagnosis with and pharmacotherapy for ADHD or PBD. Using Gergen's (1997) relational perspective I argued that mothers' knowledge and experiences of ADHD and PBD were not individually constructed, but were linguistically and discursively constituted through various social interactions and relationships, including family, spirituality and faith, community norms, and expert systems of knowledge. Mothers' narratives revealed the complexity of children's behavioral and emotional problems, the daily trials of living through these problems, how they coped with adversity and developed survival strategies, and how they interacted with various institutional authorities involved in evaluating, diagnosing, and encouraging pharmaceutical intervention for children's behavior. The findings highlight the ways in which mothers' social interactions and relationships introduced a scientific language and discourse for explaining children's behavior as mental illness, the discordances between expert systems of knowledge and mothers' understandings, and how discordances reflected mothers' ‘microsources of power’ for producing their own stories and experiences. ^ In the second manuscript presented here, I documented the ways in which structural factors, including gender, race/ethnicity, and socioeconomic status, coupled with a unique cultural and social standpoint (Collins, 1990/2009) influenced the strategies this group of African American mothers employed to understand and respond to ADHD or PBD. The most salient themes related to mother-child relationships coalesced around mothers' beliefs about the etiology of ADHD and PBD, ‘conceptualizing responsibility,’ and ‘protection-survival.’ The findings suggest that even though mothers' strategies varied, they were in pursuit of a common goal. Mothers' challenged the status quo, addressing children's behavioral and emotional problems in the ways that made the most sense to them, specifically protecting their children from further marginalization in society more so than believing these were the best options for their children.^

Puerperal Fever from Hippocrates to Pasteur

The death of a mother in childbirth leaving a newborn deserted is a sort of a desecration. This was a frequent event for early physicians. It was felt to be caused by miasmas or punishment from the gods. DaVinci felt the cause was milk stasis, Hippocrates - lochia, Virchow - weather. Then came Semmelweis, Pasteur and Lister. They started a battle with ignorance, hospital administration, budget and academic politics. Ending with the murder of Semmelweis!

First Trimester Screening and its Impact on Uptake of Diagnostic Testing

Introduction: First Trimester Screening (FTS) combines maternal age with fetal nuchal translucency (NT) and maternal analytes to identify pregnancies at an increased risk for Down syndrome and trisomy 18. Though the accuracy of this screening is high, it cannot replace the conclusive accuracy of prenatal diagnostic testing (PDT). Since FTS has been available, a decrease in the number of women who pursue PDT has been observed. This study sought to determine if there has been a significant change in the amount of PDT performed in our clinics, if the type of FTS result affects the patient’s decision regarding PDT, and what the patient’s intentions are regarding PDT. Material and Methods: A database review was performed for the two years prior and the two years after the January 2007 American College of Obstetricians and Gynecologists (ACOG) guidelines regarding FTS were issued. We compared the number of women who were AMA and the number of women who were AMA and had PDT between those time periods. We also determined the number of positive and negative FTS results, and determined how many of those patients had PDT. Finally, we surveyed our patients and referring physicians to determine: what the patient understands about FTS, what the patient’s intentions are regarding FTS, and how physicians present the option of FTS to their patients. Results: We determined that there was a 19.6% decrease in the amount of PDT performed when we compared the two time periods at our three specified clinics. Many of our patients were against having PDT prior to their genetic counseling session, but after they received genetic counseling, 76% of our population became open to the possibility of having PDT. Conclusion: Similar to previous studies, we determined that there has been a significant decrease in the number of PDT procedures performed at our clinics, which coincides with the release of the January 2007 ACOG statement regarding FTS. While our patients regarded FTS as a way to gain early information about their pregnancy in a non-invasive manner, they also stated they would use their results as a way to aid in their decision regarding PDT.

The Role of Acidic Fibroblast Growth Factor and Fibroblast Growth Factor Receptor 4 in High Grade Serous Carcinoma

Background: High grade serous carcinoma whether ovarian, tubal or primary peritoneal, continues to be the most lethal gynecologic malignancy in the USA. Although combination chemotherapy and aggressive surgical resection has improved survival in the past decade the majority of patients still succumb to chemo-resistant disease recurrence. It has recently been reported that amplification of 5q31-5q35.3 is associated with poor prognosis in patients with high grade serous ovarian carcinoma. Although the amplicon contains over 50 genes, it is notable for the presence of several members of the fibroblast growth factor signaling axis. In particular acidic fibroblast growth factor (FGF1) has been demonstrated to be one of the driving genes in mediating the observed prognostic effect of the amplicon in ovarian cancer patients. This study seeks to further validate the prognostic value of fibroblast growth receptor 4 (FGFR4), another candidate gene of the FGF/FGFR axis located in the same amplicon. The emphasis will be delineating the role the FGF1/FGFR4 signaling axis plays in high grade serous ovarian carcinoma; and test the feasibility of targeting the FGF1/FGFR4 axis therapeutically. Materials and Methods: Spearman and Pearson correlation studies on data generated from array CGH and transcriptome profiling analyses on 51 microdissected tumor samples were used to identify genes located on chromosome 5q31-35.3 that showed significant correlation between DNA and mRNA copy numbers. Significant correlation between FGF1 and FGFR4 DNA copy numbers was further validated by qPCR analysis on DNA isolated from 51 microdissected tumor samples. Immunolocalization and quantification of FGFR4 expression were performed on paraffin embedded tissue samples from 183 cases of high-grade serous ovarian carcinoma. The expression was then correlated with clinical data to assess impact on survival. The expression of FGF1 and FGFR4 in vitro was quantified by real-time PCR and western blotting in six high-grade serous ovarian carcinoma cell lines and compared to those in human ovarian surface epithelial cells to identify overexpression. The effect of FGF1 on these cell lines after serum starvation was quantified for in vitro cellular proliferation, migration/invasion, chemoresistance and survival utilizing a combination of commercially available colorimetric, fluorometric and electrical impedance assays. FGFR4 expression was then transiently silenced via siRNA transfection and the effects on response to FGF1, cellular proliferation, and migration were quantified. To identify relevant cellular pathways involved, responsive cell lines were transduced with different transcription response elements using the Cignal-Lenti reporter system and treated with FGF1 with and without transient FGFR4 knock down. This was followed by western blot confirmation for the relevant phosphoproteins. Anti-FGF1 antibodies and FGFR trap proteins were used to attempt inhibition of FGF mediated phenotypic changes and relevant signaling in vitro. Orthotopic intraperitoneal tumors were established in nude mice using serous cell lines that have been previously transfected with luciferase expressing constructs. The mice were then treated with FGFR trap protein. Tumor progression was then followed via bioluminescent imaging. The FGFR4 gene from 52 clinical samples was sequenced to screen for mutations. Results: FGFR4 DNA and mRNA copy numbers were significantly correlated and FGFR4 DNA copy number was significantly correlated with that of FGF1. Survival of patients with high FGFR4 expressing tumors was significantly shorter that those with low expression(median survival 28 vs 55 month p< 0.001) In a multivariate cox regression model FGFR expression significantly increased risk of death (HR 2.1, p<0.001). FGFR4 expression was significantly higher in all cell lines tested compared to HOSE, OVCA432 cell line in particular had very high expression suggesting amplification. FGF1 was also particularly overexpressed in OVCA432. FGF1 significantly increased cell survival after serum deprivation in all cell lines. Transient knock down of FGFR4 caused significant reduction in cell migration and proliferation in vitro and significantly decreased the proliferative effects of FGF1 in vitro. FGFR1, FGFR4 traps and anti-FGF1 antibodies did not show activity in vitro. OVCA432 transfected with the cignal lenti reporter system revealed significant activation of MAPK, NFkB and WNT pathways, western blotting confirmed the results. Reverse phase protein array (RPPA) analysis also showed activation of MAPK, AKT, WNT pathways and down regulation of E Cadherin. FGFR trap protein significantly reduced tumor growth in vivo in an orthotopic mouse model. Conclusions: Overexpression and amplification of several members of the FGF signaling axis present on the amplicon 5q31-35.3 is a negative prognostic indicator in high grade serous ovarian carcinoma and may drive poor survival associated with that amplicon. Activation of The FGF signaling pathway leads to downstream activation of MAPK, AKT, WNT and NFkB pathways leading to a more aggressive cancer phenotype with increased tumor growth, evasion of apoptosis and increased migration and invasion. Inhibition of FGF pathway in vivo via FGFR trap protein leads to significantly decreased tumor growth in an orthotopic mouse model.

Addressing Obesity: Fear of Crime, Perceptions of Disorder and Disaparities in Child and Adolescent Use of Public Parks

Abstract The objectives of this study were: 1) To determine factors which inhibit and facilitate child and adolescent use of outdoor spaces for healthy physical activity by race and ethnicity in four Houston communities and 2) To propose guidelines for encouraging and maintaining child and adolescent outdoor physical activity. Using local health data and Houston Police Department crime statistics, four communities were identified for the study that had the highest concentration of crime and the racial/ ethnic groups of interest. The researchers then identified public parks in the communities. At least two parks were observed in each of the four communities from 2010 to 2011 during spring, summer, fall and winter. The parks were observed for use by children and adolescents and to describe the condition of the park spaces. The communities were Alief (Asian), Sunnyside (Black), Eldridge- West Oaks (White) and Northside- Northline (Hispanic). Observations were made at varying hours of both day and night, weekdays and weekends. Photographs were taken and the condition of the spaces noted in detail. One hundred and twenty persons, 18 years and over, using the spaces or otherwise in these communities were conveniently sampled and interviewed about their health and the extent to which they, or any children or adolescents under their care, used the outdoor spaces of interest. Data were analyzed qualitatively and with basic descriptive statistics. The photographs, journal notes and observation notes of all investigators and key personnel were analyzed. Interview data were also coded to identify patterns and themes in the responses. The findings indicate disparities in the quality and quantity of park equipment and the maintenance of the areas. Where perceptions of disorder were described, there was often visible evidence to support the perceptions. In many cases, residents' perceptions of crime were corroborated by police data. While interview reports did not seem to support the expectation that the condition of the parks was a significant deterrent to their use by children and adolescents, the condition of the parks might be said to limit the extent of that use. Specific reports of disorder that inhibited use included hearing gunfire, seeing drug dependent homeless persons and/or suspected prostitutes in an area.

Studies of subcellular localization and complex formation of the Agrobacterium tumefaciens transport ATPase VirB11

The VirB11 ATPase is an essential component of an Agrobacterium tumefaciens type IV bacterial secretion system that transfers oncogenic nucleoprotein complexes to susceptible plant cells. This dissertation investigates the subcellular localization and homo-oligomeric state of the VirB11 ATPase in order to provide insights about the assembly of the protein as a subunit of this membrane-associated transfer system. Subcellular fractionation studies and quantitative immunoblot analysis demonstrated that $\sim$30% of VirB11 partitioned as soluble protein and $\sim$70% was tightly associated with the bacterial cytoplasmic membrane. No differences were detected in VirB11 subcellular localization and membrane association in the presence or absence of other transport system components. Mutations in virB11 affecting protein function were mapped near the amino terminus, just upstream of a region encoding a Walker 'A' nucleotide-binding site, and within the Walker 'A' motif partitioned almost exclusively with the cytoplasmic membrane, suggesting that an activity associated with nucleotide binding could modulate the affinity of VirB11 for the cytoplasmic membrane. Merodiploid analysis of VirB11 mutant and truncation derivatives provided strong evidence that VirB11 functions as a homo- or heteromultimer and that the C-terminal half of VirB11 contains a protein interaction domain. A combination of biochemical and molecular genetic approaches suggested that VirB11 and the green fluorescence protein (GFP) formed a mixed multimer as demonstrated by immunoprecipitation experiments with anti-GFP antibodies. Second, a hybrid protein composed of VirB11 fused to the N-terminal DNA-binding domain of bacteriophage $\lambda$ cI repressor conferred immunity to $\lambda$ superinfection, demonstrating that VirB11 self-association promotes dimerization of the chimeric repressor. A conserved Walker 'A' motif, though required for VirB11 function in T-complex export, was not necessary for VirB11 self-association. Sequences in both the N- and the C-terminal halves of the protein were found to contribute to self-association of the full length protein. Chemical cross-linking experiments with His$\sb6$ tagged VirB11 suggested that VirB11 probably assembles into a higher order homo-oligomeric complex. ^